Birth Weight Quartile Research Articles

Fear of Childbirth Impairs Breastfeeding Success Independent of Mode of Birth.

Background: The good qualities of breastfeeding are well known. The aim of this study was to closely examine the impact of specific maternal, prenatal, obstetric, and early neonatal factors on the success of breastfeeding. Materials and Methods: We used data from the Kuopio Birth Cohort study and analyzed 2,521 online questionnaires, which were answered by women 1 year after giving birth. Breastfeeding variables were divided into successful breastfeeding (breastfeeding exclusively with one's own breast milk ≥4 months or breastfeeding with formula ≥6 months) and poor breastfeeding (breastfeeding exclusively with one's own milk <4 months and duration of all breastfeeding <6 months) for univariate and multivariable analyses. Results: In this study, 97.8% (N = 2,466) reported breastfeeding their newborns for ≥1 postnatal week, and 75.2% (N = 1,896) breastfed newborns for ≥6 months. The rate of breastfeeding for ≥6 months increased from 71.3% to 84.7% between 2013 and 2020. In the multivariable analysis, poor breastfeeding success was associated most significantly with smoking during pregnancy (adjusted odds ratio [aOR] 4.64; 95% confidence interval [CI] 2.75-7.81), twin pregnancy (aOR 4.13; 95% CI: 2.10-8.15), maternal obesity (body mass index > 35) (aOR 3.27; 95% CI: 2.15-4.99), fear of childbirth (aOR 2.80; 95% CI: 1.89-4.13), and birth during the period of 2013-2014 (aOR 2.94; 95% CI: 2.08-4.14) or 2015-2016 (aOR 2.62; 95% CI: 1.85-3.70). Other significant factors related to poor success were younger maternal age, nonmarried family relationships, passive or quitting smoking before or in the first trimester, any hypertensive disorder during pregnancy, birth by nonelective cesarean, and lowest or highest quartiles of birth weight. Conclusions: Mother's fear of childbirth is strongly associated with the poor breastfeeding success even after controlling for mode of birth.

Does fetal size affect maternal perception of fetal movements? Evidence from an individual participant data meta-analysis.

Maternal perception of fetal movements during pregnancy are reassuring; however, the perception of a reduction in movements are concerning to women and known to be associated with increased odds of late stillbirth. Prior to full term, little evidence exists to provide guidelines on how to proceed unless there is an immediate risk to the fetus. Increased strength of movement is the most commonly reported perception of women through to full term, but perception of movement is also hypothesized to be influenced by fetal size. The study aimed to assess the pattern of maternal perception of strength and frequency of fetal movement by gestation and customized birthweight quartile in ongoing pregnancies. A further aim was to assess the association of stillbirth to perception of fetal movements stratified by customized birthweight quartile. This analysis was an individual participant data meta-analyses of five case-control studies investigating factors associated with stillbirth. The dataset included 851 cases of women with late stillbirth (>28 weeks' gestation) and 2257 women with ongoing pregnancies who then had a liveborn infant. The frequency of prioritized fetal movement from 28 weeks' gestation showed a similar pattern for each quartile of birthweight with increased strength being the predominant perception of fetal movement through to full term. The odds of stillbirth associated with reduced fetal movements was increased in all quartiles of customized birthweight centiles but was notably greater in babies in the lowest two quartiles (Q1: adjusted OR: 9.34, 95% CI: 5.43, 16.06 and Q2: adjusted OR: 6.11, 95% CI: 3.11, 11.99). The decreased odds associated with increased strength of movement was present for all customized birthweight quartiles (adjusted OR range: 0.25-0.56). Increased strength of fetal movements in late pregnancy is a positive finding irrespective of fetal size. However, reduced fetal movements are associated with stillbirth, and more so when the fetus is small.

Birth Weight in Consecutive Pregnancies and Maternal Cardiovascular Disease Mortality Among Spontaneous and Iatrogenic Term Births: A Population-Based Cohort Study.

Knowledge on the association between offspring birth weight and long-term risk of maternal cardiovascular disease (CVD) mortality is often based on firstborn infants without consideration of women's consecutive births. We studied long-term CVD mortality according to offspring birth weight patterns among women with spontaneous and iatrogenic term deliveries in Norway (1967-2020). We constructed birth weight quartiles (Qs) by combining standardized birth weight with gestational age in quartiles (Q1, Q2/Q3, and Q4) for the women's first 2 births. Mortality was estimated using Cox regression and expressed as hazard ratios (HRs) with 95% confidence intervals (CIs). Changes in offspring birth weight quartiles were associated with long-term maternal CVD mortality. Compared with women who had 2 term infants in Q2/Q3, women with a first offspring in Q2/Q3 and a second in Q1 had higher mortality risk (HR=1.33, 95% CI: 1.18, 1.50), while risk was lower if the second offspring was in Q4 (HR=0.78, 95% CI: 0.67, 0.91). The risk increase associated with having a first infant in Q1 was eliminated if the second offspring was in Q4 (HR=0.99, 95% CI: 0.75, 1.31). These patterns were similar for women with iatrogenic and spontaneous deliveries. Inclusion of information from subsequent births revealed heterogeneity in maternal CVD mortality which was not captured when using only information based on the first offspring.

Association between infant birthweight and pelvic floor muscle strength: a population-based cohort study

BackgroundTo assess the relationship between infant birthweight and pelvic floor muscle (PFM) strength in China.MethodsWe performed a retrospective, single-center cohort study of 1575 women delivering vaginally between January 2017 and May 2020. All participants completed pelvic floor examinations within 5–10 weeks after delivery and were evaluated for PFM strength, which was estimated by vaginal pressure. Data were collected from electronic records. We evaluated the association between infant birthweight and vaginal pressure through multivariable-adjusted linear regression analysis. We also performed subgroup analyses stratified by potential confounders.ResultsVaginal pressure decreased as the quartile of birthweight increased (P for trend < 0.001). Beta coefficients were -5.04 (95%CI -7.98 to -2.1), -5.53 (95%CI -8.5 to -2.57), -6.07 (95%CI -9.08 to -3.07) for birthweight quartile 2–4, respectively (P for trend < 0.001), independent of age, postpartum hemorrhage, and the number of vaginal deliveries. In addition, the results of subgroup analyses showed the same patterns across strata.ConclusionsThis study demonstrates that infant birthweight was associated with decreased vaginal pressure in women after vaginal delivery and could be considered a risk factor for decreased PFM strength in the population with vaginal delivery. This association may provide an extra basis for appropriate fetal weight control during pregnancy, and for earlier pelvic floor rehabilitation of postpartum women delivering babies with larger birthweight.

Birth Weight and Adult Obesity Index in Relation to the Risk of Hypertension: A Prospective Cohort Study in the UK Biobank.

Objectives: To investigate the association between birth weight and the risk of hypertension, and to examine the interaction between birth weight and the adult obesity index.Methods: We included 199,893 participants who had birth weight data and no history of hypertension at baseline (2006–2010) from the UK Biobank. A multivariate cubic regression spline was used to visually explore the dose-response relationship. Multivariate Cox proportional hazard regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs).Results: We observed a nonlinear inverse association between birth weight and hypertension. The risk for hypertension decreased as birth weight increased up to approximately 3.80 kg. Compared with the participants with the fourth quintile of birth weight (3.43–3.80 kg), those with the first quartile of birth weight (<2.88 kg) were associated with a 25% higher risk of hypertension [HR 1.25; 95% CI (1.18–1.32)]. In addition, the participants with birth weight <2.88 kg and body mass index ≥30 kg/m2 had the highest risk [HR 3.54; 95% CI (3.16–3.97); p for interaction <0.0001], as compared with those with birth weight between 3.43–3.80 kg and body mass index between 18.5–25.0 kg/m2. These associations were largely consistent in the stratified and sensitivity analyses.Conclusion: Our findings indicate that lower birth weight is nonlinearly correlated with higher risk of hypertension, and birth weight between 3.43–3.80 kg might represent an intervention threshold. Moreover, lower birth weight may interact with adult obesity to significantly increase hypertension risk.

PFAS concentration during pregnancy in relation to cardiometabolic health and birth outcomes

IntroductionPoly- and perfluoroalkyl substances (PFAS) are persistent organic pollutants with pervasive exposure and suspected associations with metabolic abnormalities and adverse pregnancy outcomes. The goal of the present study was to examine the relationship between serum-PFAS concentrations measured in late pregnancy with relevant outcomes. MethodsThe study sample included 433 pregnant women enrolled in the Vanguard Pilot Study of the National Children's Study. Six PFAS were measured in primarily third trimester serum, as well as fasting insulin, total cholesterol, and triglycerides. The PFAS were examined in quartiles in relation to serum biomarkers, gestational age at birth and birth weight standardized for gestational age using multivariable-adjusted regression models. ResultsOver 98% of the study population had detectable concentrations of four of the PFAS, and concentrations varied by race/ethnicity. Total cholesterol was positively associated with PFDA, PFNA, and PFOS, and triglycerides with PFDA, PFNA, PFOS, and PFOA, but PFAS were not associated with fasting insulin in adjusted models. Only PFNA was associated with an increased odds of birth at <37 weeks gestation. PFAS were generally not associated with birth weight, though PFHxS was associated with the first quartile of birth weight among males only. ConclusionsThis study of pregnant U.S. women supports the ubiquitous exposure to PFAS and positive associations between PFAS exposure with serum-lipid concentrations. PFAS were largely unassociated with gestational age at birth and birth weight, though PFNA was associated with preterm birth. The results support the vulnerability to PFAS exposure of pregnancy.

Association between neonatal birthweight and risk of maternal glucose intolerance after gestational diabetes mellitus.

Aims/IntroductionTo evaluate whether the neonatal birthweight (NBW) is associated with early postpartum glucose intolerance in women with gestational diabetes mellitus.Materials and MethodsA total of 1,113 women diagnosed with gestational diabetes mellitus who completed an oral glucose tolerance test at 6–9 weeks postpartum between 1 April 2014 and 8 January 2020 were included in this observational prospective cohort study. They were grouped by neonatal birthweight quartiles, and the odds ratios of postpartum glucose intolerance for different levels of neonatal birthweight were assessed.ResultsA lower NBW quartile was associated with an increased maternal risk of postpartum glucose intolerance after gestational diabetes mellitus. The adjusted odds ratios for maternal glucose intolerance were 1.69 (95% confidence interval 1.13–2.51) in the lowest NBW quartile (NBW 1,980–2,930 g) when compared with the highest NBW quartile (NBW 3,410–4,610 g). The association between lower NBW and maternal glucose intolerance was significantly stronger in women who delivered a girl. Additionally, NBW ≥3,100 g appears to be associated with a lower risk of maternal glucose intolerance postpartum.ConclusionsOur findings suggest that low NBW is a previously unrecognized risk factor for maternal glucose intolerance after gestational diabetes in early postpartum in South China.

Effect of maternal active smoking during pregnancy on the trajectory of childhood body mass index: A multilevel analysis using quartiles of birthweight.

INTRODUCTIONMaternal active smoking during pregnancy is associated with childhood obesity; however, whether maternal active smoking affects childhood body mass index (BMI) according to birthweight has not been examined.METHODSThe study participants were 1955 women and their single-born infants, born between 1 April 1991 and 31 March 2003, in Koshu City, Japan, for whom complete data for birthweight, pre-pregnancy maternal BMI and pregnancy smoking status were available. Maternal smoking status during pregnancy was recorded using a questionnaire at the time of pregnancy registration. Childhood BMI was estimated by the BMI z-score, established by the World Health Organisation. Birthweight quartiles were grouped by sex and parity (first vs second or higher). Multilevel analysis, including both the individual and time as different level variables by each birthweight quartile, was used to describe the trajectories of BMI z-scores for statistical analyses.RESULTSIn every quartile group, although children born to smoking mothers were leaner at birth, their BMI z-score increased around the age of 3 years. These children were larger than children born to non-smoking mothers. Significant interactions between maternal active smoking during pregnancy and child’s age were seen in those in the first and second quartiles of birthweight. Moreover, rapid growth in infancy was observed in the second quartile of birthweight.CONCLUSIONSThe effect of maternal active smoking during pregnancy on childhood growth was more apparent among children in the second quartile of birthweight.

7 Effect of piglet birth weight and drying on post-natal changes in rectal temperature

Abstract The objective of this study was to evaluate the effects of piglet birth weight and drying piglets at birth on post-natal rectal temperatures using a CRD with 2 treatments: 1) Drying (not dried vs. dried at birth with a desiccant); 2) Birth weight [4 within-litter birth weight quartiles (Q1: 1.13 ± 0.33 kg, Q2: 1.43 ± 0.28 kg, Q3: 1.62 ± 0.28 kg, Q4: 1.81 ± 0.28 kg)]. Sows (26) and litters (281 piglets) were randomly allotted to drying treatment and were housed in farrowing crates with a heat lamp; room temperature was set at 22.8°C. Piglets were weighed at birth and rectal temperature measured at 0, 15, 30, 45, 60, 90, 120, 180, 240, and 1440 min after birth. Data were analyzed using PROC MIXED of SAS (SAS Inst. Inc., Cary, NC); the model included fixed effects of litter birth weight quartile and drying treatment and interaction, and time (repeated measure), and random effect of sow. Mean piglet birth weight and rectal temperature at birth were 1.49 ± 0.39 kg and 39.2 ± 0.43°C, respectively. There were no drying by birth weight treatment interactions. Temperatures were similar (P &amp;gt; 0.05) for the drying and birth weight treatments at birth and 240 and 1440 min (Table 1). Drying increased (P &amp;lt; 0.05) rectal temperature from 15 to 180 min; the greatest difference was at 45 min (2.4°C). Temperatures were similar (P &amp;gt; 0.05) for Q2, 3, and 4 from 15 to 180 min. Quartile 1 had a lower (P &amp;lt; 0.05) temperature than the 3 heavier quartiles from 15 to 180 min, except at 120 min when temperatures were similar for Q1 and 2. The lightest piglets exhibited the greatest post-natal temperature decline and drying of piglets at birth reduced the post-natal temperature decline in piglets of all weights.

4 Effect of Piglet Birth Weight on Post-Natal Changes in Body Temperature.

Low post-natal body temperature is a predisposing factor for piglet mortality. This study investigated the effect of birth weight on piglet body temperature over 24 h after birth under typical conditions. Sows were in crates within a pen (total pen floor area for sow and piglets was 3.52 m2). Room temperature was set at 22.8°C; there was one heat lamp on one side in the middle of the pen. A total of 352 piglets from 35 litters (172 barrows; 180gilts) were used. Piglets were weighed at birth; rectal temperature was measured at birth and 15, 30, 45, 60, 90, 120, 180, and 240 min, and 24 h after birth. Data were divided into birth weight quartiles (Q1: 0.48-1.16 kg, Q2: 1.18-1.42 kg, Q3: 1.44-1.62 kg, Q4: 1.64-2.46 kg). Body temperature data were not normally distributed and were transformed using PROC RANK of SAS (SAS Inst. Inc., Cary, NC); a repeated measures analysis was carried out with PROC MIXED; the model included fixed effects of weight quartile, time of measurement (repeated measure), sow, and gender, and the random effect of farrowing date. Mean weight and rectal temperature at birth were 1.40 ± 0.35kg and 39.0 ± 0.91°C, respectively. Body temperature decreased after birth; the greatest reduction was at 30 min after birth (-4.4 ± 1.61°C lower than birth temperature; P < 0.05). Subsequently, temperatures increased but were below (P < 0.05) birth temperature at 240 min and 24 h (-0.9 ± 1.16°C and -0.5 ± 1.04°C, respectively). There was no effect (P > 0.05) of gender on temperature at any time. Temperature of Q1 was lower (P < 0.05) than that for Q3 and Q4 at most measurement times; temperatures for Q2 were intermediate to but not always different (P > 0.05) from Q1 and Q3. Differences between mean temperature for Q1 and the other quartiles increased from birth (38.8, 39.0, 39.1, and 39.2 for Q1 to Q4, respectively; SEM 0.17; P < 0.05)) to 90 min after birth (35.3, 36.8, 37.4, and 37.5, respectively; SEM 0.27; P < 0.05). Subsequently, differences in mean temperatures between the quartiles decreased but was still lower for Q1 than Q4 at 24 h (38.4, 38.6, 38.8, and 38.9, respectively; SEM 0.08; P < 0.05). These results highlight that all piglets experienced decreased body temperature after birth and that the lightest pigs (i.e., ≤1.16 kg birth weight) showed the greatest decrease and the slowest recovery.

Components of Metabolic Syndrome at 22 years of Age - Findings From Pune Low Birth Weight Study.

To study the early markers of Metabolic syndrome in a cohort of low birth weight (LBW) children followed up since birth, at the age of 22 years. Prospective cohort study. Tertiary-care hospital. Neonates weighing less than 2000 g discharged from a neonatal special care unit were followed up prospectively; 153 cases and 77 controls were assessed at 22 years of age. Fasting, 30 minute and 120 minute glucose and insulin after a bolus of 75g of glucose was determined. Insulin resistance was calculated. A lipid profile was also done. Anthropometric measurements were taken and abdominal fat was determined by magnetic resonance imaging. Prevalence of the five components of Metabolic Syndrome as described by the International Diabetic Federation (IDF). 65.1% of the cohort was born small for gestational age. All three components of Metabolic syndrome were present in only three cases and none of the controls. However, two components were present in 25 (16.4%) cases and 5 (6%) controls (P=0.039). Cases in the lowest quartile of birthweight who became big at 22 years had significantly higher fasting insulin (P=0.001), Homeostatic Model Assessment - Insulin Resistance (Homa-IR) (P=0.001) and higher systolic blood pressure. Sum of skinfold thickness at 4 sites correlated significantly with fasting insulin and HOMA-IR, and was a stronger correlate compared to BMI, waist circumference and MRI fat. There was no difference in the biochemical parameters between appropriate for gestational age and small for gestational age infants. Prevelence of three or more components of Metabolic syndrome was low in LBW children at 22 years, but of two components was high. Those 'Small at birth and big at 22 years' had high insulin resistance.

Impact of Birth Weight and Smoking on Lung Function in Patients with Asthma, COPD, and Healthy Volunteers.

Birth weight (BW) is an important factor for determining the development of the respiratory system. The majority of research analyzed the impact of BW on lung function in youth. BW influence and smoking on lung function in adults with asthma and COPD is an interesting issue. The aim of the study was to investigate relationships between BW, smoking, and lung function in adult healthy individuals and diagnosed with asthma or COPD. Four hundred seventy-nine subjects were divided into 5 groups: 123 healthy non-smokers, 180 healthy smokers, 72 non-smoking asthmatics, 57 smoking asthmatics, and 47 COPD patients. Relationships between 4 BW quartiles and lung function was analyzed with respect to smoking. Impact analyzes of BW, smoking, and asthma on FVC% revealed that asthma is the only significant differentiating factor in this spirometric parameter (p < 0.01). FEV1% was significantly influenced by asthma and BW, and FEV1/ FVC% was exclusively influenced by asthma. Spirometric parameters increased proportionally to particular BW quartiles in healthy non-smokers group; however optimal BW quartile predicting increase of parameters was 2751-3250 g. In asthma, BW quartile predicting the increase of spirometric parameters was 3251-3750 g, but BW quartile predicting decrease of FEV1/FVC% was 2751-3250 g. The comparison of results between COPD group and results from other 4 groups showed that values of all parameters in patients with COPD did not change proportionally to all quartiles of BW. In terms of FEV1/FVC%, the proportional increase of parameter in BW quartile 2751-3250 g was observed. BW, as independent factor influences on spirometric parameters of healthy individuals, patients with asthma, COPD in a differentiated manner depending on quartile of BW rather than on simple linear increase of BW, regardless of smoking.

PS-273 The Relationship Between Infant Birth Weight And Neonatal Body Composition

Background and aims Birth weight has been used as a marker of adiposity in neonates. Ponderal index incorporates infant length and is used in place of body mass index (BMI) in infants. Skinfold thickness and anthropometric measurements can be unreliable in the first few days of life. Infant body composition can be measured using air displacement plethysmography. Our aim was to explore the relationship between birth weight and neonatal body composition. Methods Infant birth weight and anthropometry were recorded. Infant body composition was measured within 3 days of delivery using air displacement plethysmography (PEA POD, Cosmed, Rome, Italy). Term infants born between 37–42 weeks were included in analysis. Data were analysed using SPSS Statistics 19. Results Measurements were performed on 467 (227 (49%) male and 240 (51%) female) term neonates (37–42 weeks) within the first 72 h of life. Mean birth weight and percentage body fat was 3.58 kg and 9.7% in males and 3.42 kg and 11.3% in females. Infants in the top quartiles of birth weight had higher body fat percentage. A multiple regression was run to predict body fat percentage from birth weight, gestation and gender. 35.7% of variance could be explained by these variables. Conclusions Birth weight, gestation and gender only have a moderate effect size on infant body fat percentage at birth, therefore birth weight is not a reliable marker of infant adiposity.

Changes in fetal Doppler indices as a marker of failure to reach growth potential at term

To evaluate whether changes in the middle cerebral artery (MCA), umbilical artery (UA) and cerebroplacental ratio (CPR) Doppler indices at term might be used to identify those appropriate-for-gestational-age (AGA) fetuses that are failing to reach their growth potential (FRGP). This was a retrospective cohort study of data obtained in a single tertiary referral center over a 10-year period from 2002 to 2012. The UA pulsatility index (PI), MCA-PI and CPR were recorded between 37+0 and 41+6 weeks within 14 days before delivery. The Doppler parameters were converted into multiples of the median (MoM), adjusting for gestational age, and their correlation with birth-weight (BW) centiles was evaluated by means of regression analysis. Doppler indices were also grouped according to BW quartiles and compared using Kruskal-Wallis and Dunn's post-hoc tests. The study included 11576 term fetuses, with 8645 (74.7%) classified as AGA. Within the AGA group, fetuses with lower BW had significantly higher UA-PI, lower MCA-PI and lower CPR MoM values. Large-for-gestational-age (LGA) fetuses were considered as the group least likely to be growth-restricted. The CPR MoM < 5(th) centile (0.6765 MoM) in these fetuses was used as a threshold for diagnosing FRGP. Using this definition, in the AGA pregnancies the percentage of fetuses with FRGP was 1% in the 75-90(th) BW centile group, 1.7% in the 50-75(th) centile group, 2.9% in the 25-50(th) centile group and 6.7% in the 10-25(th) centile group. AGA pregnancies may present with fetal cerebral and placental blood flow redistribution indicative of fetal hypoxemia. Fetal Doppler assessment may be of value in detecting AGA pregnancies that are subject to placental insufficiency, fetal hypoxemia and FRGP. Future studies are needed to evaluate the appropriate threshold for the diagnosis of FRGP and the diagnostic performance of this new approach for the management of growth disorders.

Birth Weight and Time Spent in Outdoor Physical Activity during Adolescence

We investigated the association between birth parameters (weight, length, and head circumference) and time spent in physical activity (outdoor and indoor) and screen time (TV viewing, computer, and videogame usage) among adolescents. A longitudinal cohort study surveyed 1794 children in 2004-2005 (median age = 12.7 yr), and 752 were resurveyed 5 yr later in 2009-2010 (age = 17-18 yr). Adolescents completed detailed activity questionnaires. Parents extracted birth parameter data from their child's health record booklet. After adjusting for age, sex, ethnicity, gestational age, parental education, home ownership, exposure to passive smoking, and body mass index, 12-yr-old children in the highest compared with the lowest quartile of birth weight spent on average approximately 56 and 62 min more in total (Ptrend = 0.02) and outdoor physical activity (Ptrend = 0.02) per week, respectively. Similarly, 12-yr-old children in the high (>4000 g) versus very low (<2000 g) birth weight group spent approximately 1.3 h·wk more in outdoor activity (Ptrend = 0.02). Among those age 17-18 yr, increasing birth weight (lowest to highest quartile) was associated with greater time spent in outdoor physical activity (∼1 h·wk-1, Ptrend = 0.04). Significant associations were not observed between all birth parameters and recreational screen time. Also, no associations were observed between head circumference or birth length with physical activity and screen time. Birth weight could be a potential determinant of physical activity, but not of screen time during adolescence. Hence, this could be part of the underlying mechanism between prenatal influences and future disease risk and could have possible clinical implications.

Birthweight and cytochrome P4503A4/5 activity in obese women

Large interindividual variability in drug pharmacokinetics is a challenge in the delivery of optimal pharmacotherapy. Obesity is a confirmed source of interindividual variability in the activity of cytochrome P4503A4/5 (CYP3A4/5) [1], an important determinant of drug pharmacokinetics. In a recently published study [2], we observed a large interindividual variability in CYP3A4/5 activity within obese women. However, the magnitude of change did not correlate linearly with the magnitude of obesity or the percentage of body fat, leading to speculation that sources other than sex and body mass index are at play. The need for understanding and predicting interindividual variability within these patients is critical given the current obesity epidemic. In utero growth restriction is strongly correlated to a higher incidence of obesity during adulthood [3]. In utero growth restriction is accompanied by morphological and physiological alterations in various organs [4]. These changes, especially to the liver, may affect drug metabolism during postnatal life, resulting in interindividual variability. We hypothesize that CYP3A4/5 is functionally altered by in utero growth restriction. The objective of this study is to determine whether birthweight, a surrogate marker of in utero growth restriction, is predictive of CYP3A4/5 enzyme activity in obese women. A randomized, prospective study was conducted at the Oregon Health & Science University. The Institutional Review Board approved the study protocol, and all subjects provided written informed consent. Thirty-two obese women (18–35 years old; body mass index ≥30 kg m−2) were divided into quartiles based on their self-reported birthweight (in kilograms): (1) 3.63. There were no statistical differences in age or body mass index in the four quartiles of women. Venous blood samples were collected via an indwelling catheter at 0 (baseline), 0.25, 0.5, 1, 2, 4, 5, 6, 12 and 24 h following a single 2 mg oral dose of midazolam. Plasma was separated, and aliquots were stored at −80°C prior to analysis. Both bioanalysis and pharmacokinetics analysis were described previously [2]. A one-way ANOVA was used to examine the effect of birthweight on midazolam oral clearance. The relationship between birthweight and oral clearance was also tested using regression analysis. The CYP3A4/5 activity, measured as midazolam oral clearance, was similar among the four quartiles of birthweight (Figure 1). However, an interesting, inverted U-shaped trend was observed; clearance trended to increase as quartiles of birthweight increased until quartile 3 (normal birthweight; 3.18–3.63 kilograms), then the trend reversed as birthweight continued to increase further. In order to confirm the U-shaped trend, clearance was fitted using polynomial regression, which demonstrated a statistically significant third-order polynomial fit to birthweight (P= 0.044). Figure 1 Effect of birthweight on midazolam clearance. Each box represents 25–75 percentile data, with a line representing the median and whiskers depicting 5–95 percentile data; n= 5–11. The 95% confidence intervals (whiskers) were not ... The change in clearance that is related to growth in the womb suggests that the complex determinants of drug disposition are permanently changed by the intrauterine environment. It is striking that the nature of this observed relationship between birthweight and clearance in the present study is similar to those linking birthweight to the incidence of diseases during adulthood [5, 6]. This similarity is suggestive of the critical role played by an adverse in utero environment in drug pharmacokinetics. Clearance is of critical importance in the therapeutic use of a drug, and our data suggest that part of the biological variation in the clearance is related to historical prenatal growth patterns. Birthweight is a relatively accessible, no-cost, patient-specific parameter that could be utilized in the optimization of pharmacotherapies. Along with other patient-specific parameters, such as body mass index, age, ethnicity, race, etc, birthweight could serve as useful information to personalize medicine. Although our observation was novel, the small sample size limits our ability to reach definitive conclusions. Further studies with a larger sample size, both sexes and a wider body mass index range are required, along with recorded birthweight, to establish conclusively the relevance of birthweight information in clinical practice.

Preterm Infants of Lower Gestational Age at Birth Have Greater Waist Circumference-Length Ratio and Ponderal Index at Term Age than Preterm Infants of Higher Gestational Ages

To assess anthropometric changes from birth to hospital discharge in infants born preterm and compare with a reference birth cohort of infants born full-term. Retrospective chart review was conducted of 501 preterm and 1423 full-term infants. We evaluated birth and hospital discharge weight, length, and waist circumference (WC). WC/length ratio (WLR), ponderal index, and body mass index (BMI) were calculated. Preterm infants were categorized into quartiles (Q1-4) based on birth weight (BW). At birth mean length, WC, WLR, BMI, and ponderal index were all significantly less for preterm infants in the lowest BW quartile (Q1) than preterm infants in higher BW quartiles or full-term infants. Although their weight, length, and BMI remained significantly less at discharge, preterm infants in Q1 had a disproportionate increase in WLR and ponderal index such that at discharge their WLR and ponderal index were greater than infants in Q2-3 and comparable with infants in Q4 and full-term infants. Discharge WLR and ponderal index in Q1 were significantly higher with decreasing postmenstrual age at birth. Preterm infants of a lower birth postmenstrual age have disproportionate increases in WLR and ponderal index that are suggestive of increased visceral and total adiposity.

Placental weight in singleton pregnancies with and without assisted reproductive technology: a population study of 536 567 pregnancies

Pregnancies conceived by assisted reproductive technology (ART) are at increased risk of adverse outcomes. Previous studies have suggested increased placental weight and increased placental weight/birthweight ratio in pregnancies associated with adverse outcomes. We therefore studied the association of ART with placental weight and placental weight/birthweight ratio. We included all singleton births in the Medical Birth Registry of Norway during the period 1999-2008 (n = 536 567, including 8259 after ART). We divided placental weight and placental weight/birthweight ratio into quartiles, and calculated the proportions of ART and spontaneous pregnancies in the lowest and the highest quartile by length of gestation. Thereafter, we estimated crude and adjusted odds ratios (ORs) for being in each quartile of placental weight for ART pregnancies with spontaneous pregnancies as the reference. The analyses were repeated with ART pregnancies subgrouped into IVF or ICSI. Mean placental weight was 678.9 g in pregnancies conceived by ART, and 673.0 g in pregnancies after spontaneous conception. ART pregnancies were overrepresented in the highest quartile of placental weight and underrepresented in the highest quartile of birthweight, independent of length of gestation at delivery. Thus, placental weight/birthweight ratio was higher in ART pregnancies. For ART pregnancies, the OR for being in the highest quartile of placental weight was 1.37 (95% confidence interval 1.30-1.45) after adjustment for length of gestation, offspring birthweight, parity, fetal sex, maternal age, pre-eclampsia and diabetes. There was no difference in placental weight/birthweight ratio between IVF and ICSI pregnancies. We found larger placentas and a higher placental weight/birthweight ratio among pregnancies conceived by ART compared with spontaneous pregnancies, and the difference was independent of length of gestation at delivery and ART method.

The impact of birth weight on blood pressure and arterial stiffness in later life

Accumulating evidence suggests that low birth weight is associated with increased cardiovascular risk. However, the relationship between birth weight, blood pressure, arterial stiffness and wave reflections as putative mechanisms is controversial. Data from 882 participants (mean age 21 years) were analysed. Participants underwent a detailed physiological assessment, including anthropometric measurement, blood pressure, aortic pulse wave velocity, augmentation index (AIx) and cardiac output (CO). Analyses were conducted in men and women separately, according to birth weight quartiles and categories referenced to UK birth weight percentiles. In men, those in the lowest birth weight quartile had higher brachial SBP (P = 0.04), central pulse pressure (PP; P = 0.03) and AIx (P = 0.02). Further analysis of the low birth weight spectrum revealed that central PP (P = 0.03), AIx (P = 0.03) and peripheral vascular resistance index (P = 0.01) were higher in those in the lowest birth weight percentile, although the association with AIx disappeared after adjustment for adult height. In women, analysis by birth weight quartiles and categories referenced to UK birth weight percentiles revealed a significant positive association between birth weight and CO (P = 0.04, P = 0.02) and stroke volume (P = 0.03, P = 0.002); although these associations disappeared when body size was taken into account. There was no association between birth weight and aortic pulse wave velocity in either men or women. These data suggest that although lower birth weight is associated with altered haemodynamics in young adulthood, the associations are predominantly driven by other factors such as adult body size, rather than intrinsic structural changes within the large elastic arteries.

The Fetal Growth Restricted Baby: Definition and Outcome

Introduction: There is growing evidence that the intrauterine environment has far-reaching consequences on life-long health. Almost all studies examining this effect have relied on birth weight centile alone. The aim of this study is to describe measured body composition at birth in growth restricted infants. Methods: In a prospective birth cohort study (BASELINE study) infants were recruited antenatally. Weight, length, fat mass, fat free mass and percentage body fat (%BF) were measured at birth using air displacement body plethysmography (PEAPOD). Fetal growth restriction (FGR) was defined as customised birthweight centile < 10th. Results: Of the 1335 recruited neonates, 886 had %BF measured between day 1-4. 11.09% (n=148/1335) were categorised as having FGR. The overall mean (SD) %BF was 10.84 (4.21), range = (1.30, 30.10). Significant differences between FGR babies and normal controls were noted for ponderal index [mean (SD) 25.26 (2.99); 27.82 (3.22); p< .001]; gestational age [mean 38+5 (3.40); vs 39+6 (1.95); p=.000] and rate of neonatal unit admission [12.8% (19/148); 7.4% (88/1187), p=.033]. In the infants with FGR the mean (SD) %BF was 7.9 (3.6), compared to 11.1 (4.2) %BF in the non-FGR group. In the total sample, %BF increased linearly ((r=.455, p< .001) across the customised birthweight quartiles (p< .001)). There were significant differences in mean %BF across the quartiles of customised birthweight centiles (Mean (SD) 0-25= 8.39 (3.77)%; 26-50=10.13 (3.40)%; 51-75=11.35 (3.77)%; 76-100=13.59 (4.17)% at p< .001. Conclusion: Low birth weight and reduced customized birth weight centile are associated with an altered body composition and lower mean %BF.