Lower Pre-pregnancy BMI Research Articles

Using appropriate pre-pregnancy body mass index cut points for obesity in the Chinese population: a retrospective cohort study

BackgroundAppropriate classification of obesity is vital for risk assessment and complication prevention during pregnancy. We aimed to explore which pre-pregnancy BMI cut-offs of obesity, either BMI ≥ 25 kg/m2 as recommended by the WHO for Asians or BMI ≥ 28 kg/m2 as suggested by the Working Group on Obesity in China (WGOC), best predicts the risk of adverse maternal and perinatal outcomes.MethodsWe retrospectively reviewed 11,494 medical records for live singleton deliveries in a tertiary center in Guangzhou, China, between January 2013 and December 2016. The primary outcomes included maternal obesity prevalence, adverse maternal and perinatal outcomes. Data were analyzed using the Chi-square test, logistic regression, and diagnostics tests.ResultsAmong the study population, 824 (7.2%) were obese according to the WHO criteria for Asian populations, and this would be reduced to 198 (1.7%) based on the criteria of WGOC. Obesity-related adverse maternal and perinatal outcomes were gestational diabetes mellitus, preeclampsia, cesarean section, and large for gestational age (P < 0.05). Compared to the WGOC criterion, the WHO for Asians criterion had a higher Youden index in our assessment of its predictive value in identifying risk of obesity-related adverse outcomes for Chinese pregnant women. Women in the BMI range of 25 to 28 kg/m2 are at high risks for adverse maternal and perinatal outcomes, which were similar to women with BMI ≥ 28 kg/m2.ConclusionsA lower pre-pregnancy BMI cutoff at 25 kg/m2 for defining obesity may be appropriate for pregnant women in South China. If WGOC standards are applied to pregnant Chinese populations, a significant proportion of at-risk patients may be missed.

Maternal Anthropometric measurements, Pre-pregnancy Body Mass Index, and Fetal Growth Parameters - A Rural Experience

Background: Low pre-pregnancy BMI is considered a marker for minimal nutrient reserves, fetal growth restriction and adverse pregnancy outcome. This study was conducted to evaluate the influence of pre pregnancy BMI on fetal growth parameters. Methods: A hospital based, cross-sectional, observational study was conducted among pregnant women seeking antenatal care at Kasturba Hospital, Sewagram, a rural institute in central India. Maternal pre-pregnancy BMI was calculated and correlated with new born birth weight, birth length, chest circumference, head circumference, arm circumference and ponderal index. Results: Among 500 pregnant women of first trimester, the maternal mean Pre-pregnancy weight, height and Prepregnancy BMI were 47 ± 5.77 kg, 154.43 ± 5.39 cm and 19.78 ± 2.56 kg/m2 respectively. The mean Pre-pregnancy BMI in the LBW group was 19.25 ± 1.68 kg as compared to 19.98 ± 2.60kg in normal birth weight group with a statistically significant difference (z=3.75, P=0.001, z =25.15, P=0.000). Positive correlation was found between pre pregnancy maternal weight, and BMI with neonatal weight, neonatal length, chest circumference, head circumference and arm circumference. The association was negative with neonatal ponderal index. Mean neonatal length, ponderal index, chest circumference, head circumference a mid-arm circumference were statistically significantly associated with pre-pregnancy BMI. (F=3.797 P=0.010; F=10.623 P=0.0001; F=18.924 P=0.001; F=3.948 P=0.0001; F=3.478, P=0.016 respectively).

Pre-pregnancy BMI, gestational weight gain and body image are associated with dietary under-reporting in pregnant Japanese women.

Dietary under-reporting is a common problem when using self-reported dietary assessment tools. However, there are few studies regarding under-reporting during pregnancy. This study aimed to explore the demographic and psychosocial characteristics related to dietary under-reporting in pregnant Japanese women. A cross-sectional study was conducted between 2010 and 2011 at a university hospital in Tokyo, Japan. Nutrient intake was assessed using a self-administered Diet History Questionnaire (DHQ), which had questions about the consumption frequency and portion size of selected food items. The 24-h urinary excretion levels of urea N and K were used as the dietary protein and K intake reference values, respectively. Under-reporting of protein and K was defined as the bottom 25% of the reporting accuracy (the ratio of reported intake on the DHQ to the estimated intake based on urinary excretion). Under-reporters were defined as participants who under-reported both protein and K intake. Multiple logistic regression analysis was performed to examine the factors associated with under-reporters. Of 271 healthy women at 19-23 weeks of gestation, thirty-five participants (12·9%) were identified as under-reporters. Under-reporters had a lower pre-pregnancy BMI (adjusted OR (AOR)=0·81) and lower gestational weight gain (AOR=0·82); they also reported managing their gestational weight gain with the aim to return to their pre-pregnancy weight soon after childbirth (AOR=2·99). Healthcare professionals should consider the potential for dietary under-reporting and the possible related factors when assessing the dietary intakes of pregnant Japanese women using self-administered questionnaires.

Impact of risk factors for gestational diabetes (GDM) on pregnancy outcomes in women with GDM.

In this study, we evaluated the impact of risk factors for gestational diabetes on clinical/biochemical parameters and maternal/fetal outcomes. One hundred eighty-three (n 183) women (age 33.8±5.5years, 59% Caucasians, 41% non-Caucasians) with gestational diabetes were included in the study. Anamnestic information, anthropometric and laboratory parameters, and maternal and fetal outcomes at delivery were collected. Insulin therapy prevalence was higher in Asians vs Caucasians (p=0.006), despite lower pre-pregnancy BMI in Asians (p=0.0001) and in pre-pregnancy overweight vs normal weight patients (p=0.04). Insulin-treated patients had higher fasting OGTT glucose than patients on diet therapy (p=0.003). In multivariate analysis, Asian ethnicity, age≥35years and pre-pregnancy BMI≥25kg/m2 were independent predictors of insulin therapy. Cesarean section occurred more in women aged≥35years than<35years (p=0.02). Duration of pregnancy and age showed inverse correlation (r -0.3 p=0.013). Week of delivery was lower in patients≥35years vs patients<35years (p=0.013). Fasting OGTT glucose was higher in overweight than in normal weight patients (p=0.016). 1-h OGTT glucose was lower in obese vs normal weight (p=0.03) and overweight patients (p=0.03). Prevalence of prior gestational diabetes was higher in overweight/obese women (p=0.002). Ethnicity, age, and BMI have the heaviest impact on pregnancy outcomes.

Excessive gestational weight gain is associated with long-term body fat and weight retention at 7 y postpartum in African American and Dominican mothers with underweight, normal, and overweight prepregnancy BMI

Excessive gestational weight gain (GWG) is associated with postpartum weight retention (PPWR) and abdominal adiposity, but long-term effects are understudied in low-income and minority populations at high risk of obesity and associated sequelae. We examined associations between GWG and long-term PPWR and adiposity in a prospective cohort of African American and Dominican mothers in the Bronx and Northern Manhattan. Women (n = 302) were enrolled during pregnancy and were followed for 7 y postpartum. Linear regression was used to relate excessive GWG [greater than 2009 Institute of Medicine (IOM) guidelines] to outcomes [percentage body fat and long-term PPWR (change in weight from prepregnancy to 7 y postpartum)], adjusting for covariates and included an interaction term between prepregnancy body mass index (BMI; in kg/m(2)) and GWG. Mean ± SD prepregnancy BMI and total GWG were 25.6 ± 5.8 (42% of women had BMI ≥25) and 16.6 ± 7.8 kg (64% of women had total GWG greater than IOM guidelines), respectively. Associations between GWG and long-term PPWR and the percentage body fat varied by prepregnancy BMI (P-interaction ≤ 0.06); excessive GWG was associated with a higher percentage body fat and greater long-term PPWR in mothers with lower prepregnancy BMI. To illustrate the interaction, a predicted covariate-adjusted model, which was used to derive estimates for the percentage body fat and PPWR associated with excessive GWG, was estimated for 2 prepregnancy BMI examples. For a woman with prepregnancy BMI of 22, excessive GWG was associated with 3.0% higher body fat (P < 0.001) and a 5.6-kg higher PPWR (P < 0.001); however, for a woman with a prepregnancy BMI of 30, excessive GWG was associated with 0.58% higher body fat (P = 0.55) and 2.06 kg PPWR (P = 0.24). Long-term adiposity and PPWR in low-income African American and Dominican mothers were predicted by interacting effects of prepregnancy BMI and excessive GWG. The provision of support for mothers to begin pregnancy at a healthy weight and to gain weight appropriately during pregnancy may have important lasting implications for weight-related health in this population. This study was registered at clinicaltrials.gov as NCT00043498.

Psychosocial factors and excessive gestational weight gain: The effect of parity in an Australian cohort

Objectivespsychosocial variables can be protective or risk factors for excessive gestational weight gain (GWG). Parity has also been associated with GWG; however, its effect on psychosocial risk factors for GWG is yet to be determined. The aim of this study was to investigate if, and how, psychosocial factors vary in their impact on the GWG of primiparous and multiparous women. Design/Participantspregnant women were recruited in 2011 via study advertisements placed in hospitals, online, in parenting magazines, and at baby and children’s markets, resulting in a sample of 256 women (113 primiparous, 143 multiparous). Participants completed questionnaires at 16–18 weeks’ gestation and their pregravid BMI was recorded. Final weight before delivery was measured and used to calculate GWG. Findingsthe findings revealed that primiparous women had significantly higher feelings of attractiveness (a facet of body attitude; p=0.01) than multiparous women. Hierarchical regressions revealed that in the overall sample, increased GWG was associated significantly with lower pre-pregnancy BMI (standardised coefficient β=−0.39, p<0.001), higher anxiety symptoms (β=0.25, p=0.004), and reduced self-efficacy to eat a healthy diet (β=−0.20, p=0.02). Although higher GWG was predicted significantly by decreased feelings of strength and fitness for primiparous women (β=−0.25, p=0.04) and higher anxiety was related significantly to greater GWG for multiparous women (β=0.43, p<0.001), statistical comparison of the model across the two groups suggested the magnitude of these effects did not differ across groups (p>0.05). Conclusions/Implications for practicethe findings suggest that psychosocial screening and interventions by healthcare professionals may help to identify women who are at risk of excessive GWG, and there may be specific psychosocial factors that are more relevant for each parity group.

Maternal Vitamin D Status and Its Related Factors in Pregnant Women in Bangkok, Thailand.

BackgroundThere are few data focusing on the prevalence of vitamin D deficiency in tropical countries. ObjectivesWe determined the vitamin D status in pregnant women and examined the factors associated with vitamin D deficiency. Design and MethodsA cross-sectional study of 147 pregnant Thai women aged 18–45 years at Siriraj Hospital (a university hospital in Bangkok, Thailand) was undertaken. Clinical data and plasma levels of 25-hydroxyvitamin D [25(OH)D], intact parathyroid hormone (iPTH), calcium, albumin, phosphate and magnesium were obtained in pregnant women at delivery. ResultsThe prevalence of hypovitaminosis D [defined as 25(OH)D <75 nmol/L] in pregnant women at delivery was 75.5% (95% confidence interval (CI), 67.7–82.2%). Of these, vitamin D insufficiency [defined as 25(OH)D 50–74.9 nmol/L] was found in 41.5% (95% CI, 33.4–49.9%) and vitamin D deficiency [25(OH)D <50 nmol/L] was found in 34.0% (95% CI, 26.4–42.3%) of women. The mean 25(OH)D concentration was 61.6±19.3 nmol/L. The correlation between 25(OH)D and iPTH was weak (r = –0.29, P<0.01). Factors associated with vitamin D deficiency by multiple logistic regression were: pre-pregnancy body mass index (BMI in kg/m2, odds ratio (OR), 0.88, 95% CI 0.80–0.97, P = 0.01) and season of blood collection (winter vs. rainy, OR, 2.62, 95% CI 1.18–5.85, P = 0.02). ConclusionsVitamin D deficiency is common among pregnant Thai women. The prevalence of vitamin D deficiency increased in women who had a lower pre-pregnancy BMI and whose blood was collected in the winter. Vitamin D supplementation may need to be implemented as routine antenatal care.

A cohort study on the impacts of pre-pregnancy maternal body mass index, gestational weight gain on neonate birth status and perinatal outcomes in Fujian province

To study the impacts of pre-pregnancy maternal BMI and gestational weight gain(GWG) on pregnancy outcomes. We adopted a prospective cohort study with cluster sampling in single pregnant women, who were not with hypertension, diabetes, hyperlipidemia or other diseases in the previous history, neither did they have diseases of heart, liver, kidney, thyroid etc. related to current pregnancy. Those pregnant women who visited the prenatal nutrition clinic under 'informed consent' were surveyed with questionnaire to track their peri-natal complications, delivery mode and neonate birth outcomes etc. Pearson and partial correlations, chi-square test and binary logistic regression were used to study the association between pre-pregnancy maternal BMI, GWG and pregnancy outcomes. A total of 623 pregnant women were recruited in the cohort, with 592 (95%) of them eligible for analysis. Results from the Multivariate Logistic Regression analysis indicated that, after controlling the potential confounding factors, when compared to women with pre-pregnancy BMI between 18.5 and 24.0, the odds ratios (ORs) for low birth ponderal index (PI) were 2.34 [95% confidence interval (CI), 1.24-4.42)]among those with BMI<18.5, respectively, while 2.73 (1.12-6.68) for high birth PI among those with BMI > 24.0. Similarly, when compared to pregnant women with normal GWG(defined as weight gain range from P15 to P85 by stratification of pre-pregnancy BMI), low GWG (<P15) seemed to be the risk factor for preterm birth, low birth weight, gestational diabetes mellitus, with low birth PI [ORs as 4.85(1.35-17.51), 10.30 (2.29-46.35), 2.29 (1.07-4.93) and 2.65(1.24-5.68), respectively. High GWG (>P 85)appeared the risk factor for high birth weight, high birth PI, and gestational diabetes mellitus, with ORs as 3.83(1.74-8.44), 2.39(1.14-5.01)and 2.21(1.07-4.55), respectively. Low or high pre-pregnancy maternal BMI and GWG were associated with adverse pregnancy outcomes.

Epidemiology of Low Birth Weight in the Town of Sidi Bel Abbes (West of Algeria): A Case-Control Study

Introduction: The Low birth weight is defined as a live birth weighting less than 2500 g and it is considered to be a major determinant of the child survival, his health and development. Objective: This study examined the frequency and risk factors that influence birth weight <2.5 kg (LBW) in the region of Sidi bel Abbes (west of Algeria). Materials and methods: A descriptive prospective case-control study was done during the period of June 2012 to January 2013. Total samples were 1828 pregnant women and their newborns in neonatology department of Hospital Obstetrics and Gynecology in Sidi bel Abbes west Algeria. Results: At the end of this work, it appears a prevalence of 1828 new born, including maximum newborn babies 92.97% had birth weight 2.5 Kg or more and 128 newborns with low birth weight <2.5 Kg, or a rate of 7.02%. It was found that mean weight of newborn babies was 3386.95 ± 560.70 (g). This study confirms the close association between low birth weight newborn and prematurity, primiparity, short interpregnancy interval, multiple pregnancy, previous history of low birth weight, delayed of first antenatal visit, low pre-pregnancy BMI, gestational weight gain less than the recommendations, primary educated mothers, other complications and diseases which contributed to high prevalence of LBW included hypertension and gestational diabetes. Conclusion: It is essential to do a searching for pregnancies with higher risk of LWB like those who are primiparous or have short birth intervals, and it is also important to have better and more attentive prenatal care in order to reduce the incidence of LBW.

New International Association of the Diabetes and Pregnancy Study Groups (IADPSG) recommendations for diagnosing gestational diabetes compared with former criteria: a retrospective study on pregnancy outcome

The International Association of the Diabetes and Pregnancy Study Groups (IADPSG) Consensus Panel recommends new criteria for diagnosing gestational diabetes. We evaluated the clinical and metabolic characteristics, and pregnancy outcome, in women previously classifiable as 'normal' according to the 4th International Workshop Conference on gestational diabetes criteria, but reclassified as 'abnormal' according to the new recommendations. Using the new IADPSG criteria, 3953 pregnancies were retrospectively reclassified as 1815 women with normal glucose tolerance and 2138 with gestational diabetes, 112 (2.8%) of whom would have been classified as normal according to the older criteria. Of the 2138 women classified as abnormal by the new criteria, the 112 women now reclassified as abnormal were younger and had a lower pre-pregnancy BMI than the 2026 women who had also been classified as abnormal by the previous criteria. The 100-g oral glucose tolerance test showed significantly higher glucose levels in these 112 women than in the 1815 women reclassified as normal (P < 0.0001). Caesarean section was significantly more frequent (P < 0.01) and the ponderal index for the newborn significantly higher in these reclassified women than in those classified as normal (P < 0.0001), and their basal glucose levels correlated significantly with the ponderal index (P < 0.05). The new criteria for diagnosing gestational diabetes identified a group of women previously classifiable as normal according to the 4th International Workshop Conference criteria, but revealing metabolic characteristics and pregnancy outcomes resembling those of women who would have been considered to have gestational diabetes by the previous criteria.

Patterns and success of fetal programming among women with low and extremely low pre-pregnancy BMI

To estimate the frequency of fetal programming phenotypes among women with low BMI and the success of these programming patterns-to determine if small for gestational age (SGA) is a biologically adaptive mechanism to improve chances for infant survival. We examined the frequency of fetal programming phenotypes: SGA, large for gestational age (LGA), and adequate for gestational age (AGA) among 1,063,888 singleton live births from 1978 to 1997. We also estimated the success of fetal programming phenotypes using neonatal death as the primary study outcome. Underweight gravidas with AGA and LGA babies had elevated risk of neonatal mortality when compared to normal weight mothers, while the risk for neonatal mortality among mothers with SGA babies was reduced. The variation in relative degrees of fetal programming patterns and success observed suggests that underweight mothers are more likely to succeed in programming SGA fetuses rather than any other phenotype.

Do pregnant women exercise their pelvic floor muscles?

The aims of the present study were to assess the number of women performing pelvic floor muscle training (PFMT) during pregnancy and to compare the background variables in those exercising and in those who did not. Four hundred and sixty-seven pregnant women (response rate 84%), mean age 31.5 years (range 20-49), answered a questionnaire on general physical activity level during pregnancy including PFMT. The questionnaire was sent out in week 32 of gestation and answered within week 36. Twenty-four percent reported problems with urinary incontinence and 9% flatus/fecal incontinence. The percentages of pregnant women performing PFMT at least once a week before pregnancy and during trimesters 1, 2, and 3 were 7, 12.9, 17.6, and 17.4%, respectively. More women with lower prepregnancy BMI and with present and past pelvic girdle pain were performing regular PFMT. No significant differences were found in any other background variables. It is concluded that relatively few women perform regular PFMT during pregnancy. In conclusion, only 17% of pregnant Norwegian women reported performing PFMT during pregnancy.

The Effect Of Pre-Pregnancy Body Mass Index, Gestational Weight Gain On Pregnancy Outcomes

Background: Nutritional status of women has been considered an important prognostic indicator of pregnancy outcomes. The study aims to show the effect of various pregnancy body mass index categories and corresponding gestational weight gain on pregnancy outcomes. Materials and Methods: 270 women were included in the study. BMI was categorized and weight gain was divided into two groups normal and abnormal based on IOM's recommendation. Chi square and one way ANOVA were used in the univarate analysis of the association between weight gain and corresponding adverse outcome (cesarean, preterm labor, low birth weight). Adjusted odds ratios for adverse outcomes were determined by multiple logistic regression models, while controlling for the following factors: maternal, age, parity, education. Results: For women with pre-pregnancy BMI<19, mean birth weight of newborn was significant low. (P<0.05) The abnormal weight gain during pregnancy wasn't related to an increased risk of preterm labor or cesarean delivery but it was highly associated with LBW. (P<0.05) Conclusion: Efforts should be made to attain appropriate weight gain to reduce the likelihood of low birth weight. Hence, special attention should be paid to women with low pre-pregnancy BMI.

Hemoglobin Concentrations Influence Birth Outcomes in Pregnant African-American Adolescents

Relationships between hemoglobin concentrations and birth outcomes have not been well characterized in African-American adolescents despite the fact that this group is at a higher risk of early childbearing. To address this issue, we characterized the prevalence of anemia and maternal factors associated with anemia in pregnant African-American adolescents. A retrospective medical chart review was undertaken of 918 adolescents who had received prenatal care at an inner-city maternity clinic between 1990 and 2000. Multiple log-linear regression analyses were used to address relationships between hemoglobin and adverse birth outcomes. The prevalence of anemia during the third trimester averaged 57-66% and was substantially higher than typically reported in adolescent and adult women. Multiparity, inadequate prenatal care, low prepregnancy BMI, history of self-reported cigarette use and infection with sexually transmitted diseases were significantly associated with lower hemoglobin during pregnancy. Adolescents with pre-eclampsia had higher hemoglobin (P < 0.01). Compared with the reference group (106-120 g/L), high hemoglobin (>120 g/L) during the second and third trimester significantly increased the risk of low birth weight (risk ratio (RR) = 3.11; [CI] 1.35, 7.13), and in the second-trimester cohort only, high hemoglobin concentrations increased the risk of preterm delivery (RR = 2.33; [CI] 1.07, 5.05). A U-shaped distribution between hemoglobin concentration and adverse birth outcomes was found in the third-trimester cohort when the reference range was decreased to 96-105 g/L to adjust for potentially lower hemoglobin concentrations among the African-American population. Our results suggest that additional medical attention may be warranted in pregnant African-American adolescents with hemoglobin concentrations of <or=95 g/L or >120 g/L.

The influence of fetal and maternal factors on the distribution of birthweight

This review of common risk factors for low birthweight emphasizes the usefulness of examining the entire distribution of birthweight. Of the factors we examined, only short gestational age seemed to affect the low end of the birthweight distribution in the form of skewness. Most factors, such as maternal race, infant sex, plurality, altitude, education, and smoking seem to affect the entire birthweight distribution, indicating a generalized effect. With the exceptions of race, infant sex, parity, and altitude, these factors seemed to have similar associations with both low birthweight and infant mortality. However, only the effects of race and sex on mortality have been repeatedly studied in detail for different combinations of gestational age and birthweight. A few of the factors examined, notably infant sex and parity, have opposite associations with birthweight and infant mortality. Female infants and firstborn infants have lower birthweights than their counterparts, but are more likely to survive. For factors that significantly affect the birthweight distribution, but do not affect mortality equally across the birthweight distribution, the development and use of population-based standards may result in less misclassification of IUGR. Separate standards by infant sex, altitude, and perhaps race may lead to more accurate classification of intrauterine growth. Last, the majority of risk factors have differential effects on birthweight depending on the level of the associated factors. For example, low maternal age and low prepregnancy BMI are associated with both increased risk of low birthweight and poor infant survival. Older maternal age and high prepregnancy BMI are associated with reduced risk of low birthweight, but with increased risk of infant mortality. One possible explanation is that young maternal age and low prepregnancy BMI are associated with adverse behavioral risk factors such as cigarette smoking, whereas increased age and high prepregnancy BMI are associated with gestational diabetes, multiparity, and genetic defects. It is possible that the greater variation in birthweight at the high end of the scale is indicative of increased risk of mortality. Thus, higher birthweight does not always equal better birth outcomes.

Prenatal weight gain patterns and spontaneous preterm birth among nonobese black and white women

Evidence for the relationship of prepregnancy weight and prenatal weight gain to preterm delivery (PTD) is mixed; several important methodological issues have prevented the drawing of firm inferences. The objective of this study was to examine, by trimester, the relationship of prenatal weight gain (total, rate) to spontaneous PTD among low-income high-risk nonobese (body mass index: BMI ≤26.0) black (677) and white (338) multiparous women. Sociodemographic data, reproductive history, and reported prepregnancy weight were obtained by interview during the first prenatal visit. Weight and height were measured without shoes in light clothing, using standard anthropometric procedures. Total gain (kg) and rate of gain (kg/wk) were calculated as follows: first trimester (last weight observation during gestational ages [GA] 10–13 wks minus prepregnancy weight); second trimester (last weight during GA 24–27 wk minus first weight during 14–18 wk); third trimester (last weight prior to delivery minus first weight during GA 28–32 wk). Results revealed that >70% of PTD was at 32–36 wk GA. PTD was higher among black (12.4%) than white (8.0%) women (p=0.033). PTD was higher among white (11.9%) than black (5.1%) women with low prepregnancy BMI (p=0.027). While 45% of the women gained less than current Institute of Medicine guidelines by BMI in the first trimester, and from 22 to 37% gained less than these guidelines during the second trimester, in regression analysis neither total nor rate of gain was associated with GA or PTD. However, third trimester rate of gain (kg/wk) was positively associated with GA for all women (p=0.005) and for black women (p=0.026) with low prepregnancy BMI, but not for white women or for women with normal BMI. These data suggest that the impact of weight gain pattern on PTD varies by prepregnancy BMI, ethnicity, and trimester, and is greatest during the third trimester among women with low BMI.