Predictors Of Fetal Growth Research Articles

Effects of binge drinking on infant growth and development in an Inuit sample

Prenatal exposure to an average of 0.5 oz absolute alcohol per day (the equivalent of 7 standard drinks per week) during pregnancy has been found to be associated with numerous adverse effects on pre- and postnatal development. In the animal model, concentrated alcohol exposure has been found to lead to more adverse effects than exposure to the same total quantity of alcohol ingested in smaller doses over a longer period of time. The primary aim of this study is to determine whether, in a population where binge drinking is common but total alcohol consumption across pregnancy is low, prenatal exposure to alcohol is associated with effects on prenatal growth, visual acuity and cognitive development during infancy. The second aim is to determine which of several indicators of alcohol consumption best predicts pre- and postnatal outcomes. Data were collected from 216 Inuit women and their infants living in Nunavik, the northern region of Québec. Maternal interviews were conducted during mid-pregnancy and at 1 and 6 months postpartum. Birth weight, length, and head circumference were assessed at delivery. Visual acuity and cognitive development were assessed at 6 months of age. In this population in which infrequent heavy episodic drinking is common, even occasional binge exposure was associated with reduced prenatal growth and poorer visual acuity at 6 months of age. A simple dichotomous measure of binge drinking during pregnancy provided the best predictor of fetal growth and 6-month acuity. The population studied here is unusual in terms of its pattern of binge alcohol consumption. To our knowledge, this is the first study to observe effects of binge drinking during pregnancy on infant growth and development in a sample where the average daily alcohol intake is low (<0.5 ounces).

Hair Biomarkers as Measures of Maternal Tobacco Smoke Exposure and Predictors of Fetal Growth

Most biomarker studies of the effects of maternal smoking on fetal growth have been based on a single blood or urinary cotinine value, which is inadequate in capturing maternal tobacco exposure over the entire pregnancy. We used hair biomarkers to compare the associations of maternal self-reported smoking, hair nicotine, and hair cotinine with birth weight for gestational age (BW for GA) among active and passive smokers during pregnancy. We collected maternal hair in the immediate postpartum period and measured nicotine and cotinine concentrations averaged over the pregnancy in 444 term controls drawn from 5,337 participants in a multicenter nested case-control study of preterm birth. BW for GA Z-score and small for gestational age (SGA) were based on Canadian population-based standards. The addition of hair nicotine to multiple linear regression models containing self-reported active smoking, hair cotinine, or both explained significantly more variance in the BW for GA Z-score (p = .01, .03 and .04, respectively). Similarly, women with hair nicotine, but not cotinine, at or above the median value had a significant increase in the risk of SGA birth (odds ratio: 3.07, 95% CI: 1.25-7.52). No significant association was observed between maternal passive smoking and BW for GA based on hair biomarkers. Hair nicotine is a better predictor of reductions in BW for GA than either hair cotinine or self-report. Our negative results for passive smoking suggest that previously reported small but significant effects may be explained by misclassification of active smokers as passive smokers based on self-report.

A Low-Protein Diet during Gestation in Rats Activates the Placental Mammalian Amino Acid Response Pathway and Programs the Growth Capacity of Offspring1–3

Placental efficiency is a predictor of fetal growth and development, which is also controlled by maternal gestational health and diet. The present study investigated the effects of a gestational low-protein diet on offspring growth capacity as well as the diet’s contribution to altered expression of placental genes associated with the mammalian amino acid response (AAR) pathway. To assess these outcomes, timed-pregnant Sprague Dawley rats were fed a control (C) diet with 18% protein or a low-protein (LP) diet with 9% protein throughout gestation (Expt. 1) or throughout gestation and lactation (Expt. 2). Placentas were collected during natural delivery and quantitative RT-PCR and Western-blot analyses were performed to determine placental mRNA and protein levels. By the end of the lactation period, offspring of dams fed the LP diet had stunted growth in both experiments. mRNA expression of target genes in the AAR pathway, such as activating transcription factor-3 (Atf3), asparagine synthetase (Asns), and Sodium-dependent neutral amino acid transporter-2 (Snat2), was greater in placentas of rats fed the LP diet compared with controls, as were placental ATF4 and p-eIF2α protein levels. The increase in mRNA expression of AAR pathway-associated genes was correlated with the stunting of offspring growth (Atf3: R2 = 0.32, P = 0.086; Asns: R2 = 0.44, P < 0.05; Snat2:R2 = 0.33, P = 0.084). Our study showed that the mammalian AAR pathway in placenta is upregulated by a maternal low-protein diet and this activation may act as a cue for the fetus to develop an adaptive response suited to their predicted postnatal environment, i.e. a more favorable phenotype for their survival.

Differences in fat and lean mass proportions in normal and growth-restricted fetuses

The purpose of this study was to assess fetal subcutaneous fat and lean mass areas as predictors of fetal growth restriction. Seventeen severe fetal growth-restricted (abdominal circumference, < 2 SD) fetuses and 20 control fetuses underwent ultrasound measurements of subcutaneous fat, lean mass, and standard biometry. Thigh subcutaneous fat and lean mass were measured on enlarged ultrasound axial images (subcutaneous fat area = total cross sectional area - lean mass area [bone + muscle areas]). Subcutaneous fat and lean mass areas were expressed as a percentage of the total cross-sectional area and were normalized to femur length and head circumference. Measurements were modeled as a function of fetal growth-restriction status and week of gestation with multiple linear regression. Fetal growth-restriction fetuses showed reductions in fat and lean mass (in standard biometry) and showed a disproportionate reduction in fat mass compared with lean mass. These were all associated significantly with fetal growth restriction. Fetal growth-restricted fetuses have reduced subcutaneous fat and lean mass compared with control fetuses; a further reduction occurs in subcutaneous fat concentration compared with the reduction in lean mass when fat is normalized for body size, with either head circumference or femur length. Fat-to-bone proportions may be useful in distinguishing the small for gestational age fetus who is truly fetal growth restriction from the constitutionally small fetus.

Phosphorylated insulin-like growth factor binding protein 1 is increased in pregnant diabetic subjects.

During pregnancy, IGFs and their binding proteins (IGFBPs) are important for the growth of fetal and maternal tissues. IGFBP-1 normally circulates as a single, highly phosphorylated species (hpIGFBP-1). However, in pregnancy there are lesser phosphorylated isoforms (lpIGFBP-1) with decreased affinity for IGF-I, allowing for increased IGF bioavailability. Because regulation of IGFBP-1 is abnormal in type 1 diabetes, we examined the impact of this on IGFBP-1 and its phosphorylation status in diabetic pregnancy. We assessed IGFBP-1 in relation to birth weight, maternal weight gain, duration of diabetes, glycemic control, and the presence or absence of retinopathy in 44 diabetic and 11 nondiabetic subjects. We found that in type 1 diabetic patients there was a significant negative relationship between hpIGFBP-1 and birth weight (r = -0.42, P < 0.01) and between the ratio of hpIGFBP-1 to lpIGFBP-1 and birth weight (r = -0.38, P = 0.02) by week 18 of gestation. Multiple regression analysis confirmed that hpIGFBP-1 was the best single predictor of birth weight (R2 = 0.3, P = 0.001) in diabetic subjects using models including other parameters known to influence fetal size. In contrast to hpIGFBP-1 levels, lpIGFBP-1 levels were not associated with birth weight, but were significantly related to initial maternal BMI and maternal weight throughout gestation in diabetic subjects (r = -0.57, P < 0.001). hpIGFBP-1 levels were positively related to duration of diabetes (r = 0.38, P < 0.01). Diabetic subjects had significantly higher hpIGFBP-1 and lpIGFBP-1 levels than nondiabetic subjects (hpIGFBP-1: 215 +/- 21 vs. 108 +/- 13 microg/l, P = 0.01; lpIGFBP-1: 139 +/- 12 vs. 66 +/- 5 microg/l, P < 0.001), but the ratio of hpIGFBP-1 to lpIGFBP-1 was similar in both groups (2.1 +/- 0.3 [diabetic] vs. 1.7 +/- 0.2 [nondiabetic], NS). In summary, maternal IGFBP-1 levels were higher in diabetic than in normal pregnancies. Diabetic subjects with prolonged duration of diabetes and retinopathy had higher total IGFBP-1 levels than those with shorter disease duration. Thus hpIGFBP-1 in diabetic pregnancy is positively related to the duration of diabetes and inversely related to fetal growth, with lpIGFBP-1 being related to maternal weight and BMI. The ratio of hpIGFBP-1 to lpIGFBP-1 may be a more robust indicator of fetal outcome, since it was consistent between diabetic and nondiabetic subjects. Measurement of the different phosphorylated isoforms of IGFBP-1 may increase the usefulness of IGFBP-1 as a predictor of fetal growth in both normal and diabetic pregnancy.

Psychosocial factors and intrauterine fetal growth: a prospective study.

This study focused on the possible role of psychosocial factors on intrauterine fetal growth. Pregnant women (n = 236) completed questionnaires on daily stressors and psychosomatic symptoms three times during pregnancy; in the 11-12th week, the 23-24th week and the 35-36th week. In addition, information was obtained on the quality of the marital relationship, social support, social class, physical work load, weight of the biological parents and life-style variables (including smoking, alcohol and coffee consumption). Birth weight corrected for gestational age, sex and parity was utilized as an index of intrauterine fetal growth. This dependent measure did not appear to be affected by exposure to daily stressors or disturbed maternal well-being on any of the measuring points. Smoking appeared to be the best predictor of fetal growth, together with maternal weight and the family's socioeconomic status. These variables accounted for 10.6% of the variance. It is postulated that the absence of a relationship between stressors and fetal development may be due to the buffering effects of adequate emotional support provided by the partners and the further social network.

Relationship of maternal amino acids and proteins to fetal growth and mental development

The relationship of maternal amino acids, proteins, and certain other factors to fetal development (weight and cranial volume at birth and mental and motor scores at 8 months of age) was investigated in 129 gravidas. Maternal prepregnancy weight was significantly related to birth weight and cranial volume in the newborn. Among amino acids, glycine, lysine, and total amino acids were positively correlated with birth weight, whereas valine and threonine showed a negative correlation. Cranial volume at birth was significantly related to the level of glycine and alpha1 globulin. Other protein and amino acids which contributed to cranial volume included threonine, histidine, glutamic acid, and beta globulin, negatively correlated, whereas glutamine was positively correlated. Alpha1 globulin (negatively) and glycine (positively) made significant contributions to motor development. For mental development, alpha 1 globulin and histidine showed a negative correlation, whereas isoleucine was positively correlated. Findings indicated that the concentrations of certain maternal amino acids and proteins in the third trimester of pregnancy correlated significantly with fetal growth and development. This study suggests: (1) specific proteins or amino acids may be responsible for different developmental measures; (2) injudicious dietary restrictions in pregnancy should be avoided; (3) the determination of alpha1 globulin and a few amino acids such as glycine, lysine, and histidine in late pregancy may be used as predictors of fetal growth and development.