Fetal Growth in Early Pregnancy and Risk of Delivering Low Birth Weight Infant: Prospective Cohort Study

Abstract

Objective To determine if first trimester fetal growth is associated with birth weight, duration of pregnancy, and the risk of delivering a small for gestational age infant. Design Prospective cohort study of 38 033 pregnancies between 1999 and 2003. Setting 15 centres representing major regions of the United States. Participants 976 women from the original cohort who conceived as the result of assisted reproductive technology, had a first trimester ultrasound measurement of fetal crown-rump length, and delivered live singleton infants without evidence of chromosomal or congenital abnormalities. First trimester growth was expressed as the difference between the observed and expected size of the fetus, expressed as equivalence to days of gestational age. Main outcome measures Birth weight, duration of pregnancy, and risk of delivering a small for gestational age infant. Results For each one day increase in the observed size of the fetus, birth weight increased by 28.2 (95% confidence interval 14.6 to 41.2) g. The association was substantially attenuated by adjustment for duration of pregnancy (adjusted coefficient 17.1 (6.6 to 27.5) g). Further adjustments for maternal characteristics and complications of pregnancy did not have a significant effect. The risk of delivering a small for gestational age infant decreased with increasing size in the first trimester (odds ratio for a one day increase 0.87, 0.81 to 0.94). The association was not materially affected by adjustment for maternal characteristics or complications of pregnancy. Conclusion Variation in birth weight may be determined, at least in part, by fetal growth in the first 12 weeks after conception through effects on timing of delivery and fetal growth velocity.

The health and nutrition of young indigenous women in north Queensland – intergenerational implications of poor food quality, obesity, diabetes, tobacco smoking and alcohol use

“…There is increasing evidence from large cohort studies that early fetal growth (the first 12 weeks) predicts birth weight and other important neonatal outcomes. Using precise estimates of gestational age, Bukowski and colleagues found that variation in birth weight was at least partly determined by fetal growth in the first 12 weeks after conception through effects on timing of delivery and fetal growth velocity (25) . A central feature of fetal development is widespread cell division and folate is critical in nucleic acid synthesis.…”

HbA1c and birthweight in women with pre-conception type 1 and type 2 diabetes: a population-based cohort study

“…As there LGA was defined as birthweight ≥90th centile, and SGA as birthweight <10th centile, according to Scottish birthweight standards (by fetal sex, parity and gestational age) [24] b Adjusted model was constructed using backwards stepwise regression. All variables with p<0.5 in the univariate analysis were entered into the model, and then non-significant variables were removed iteratively (according to decreasing p value) until only those with p<0.1 remained, details of which are shown is some evidence that variation in birthweight may be at least partly determined by fetal growth within the first 12 weeks after conception [38], investigation of the association of periconception hyperglycaemia with early fetal growth is crucial for understanding the mechanisms of growth restriction or overgrowth in pregnancies of women with diabetes. In addition to maternal hyperglycaemia, other factors, such as non-smoking, higher maternal height and BMI, found to be associated with higher birthweight in offspring of women with diabetes by previous studies [27,30], were also independent significant predictors of increased birthweight in our study.…”

Ambient Air Pollution and Reproductive Health

“…For studies which considered all three pregnancy trimesters, exposures during the first and third trimesters appeared to be significantly associated with some birth outcomes. For example, Bukowski et al 2007 demonstrated in their study that variation in birth weight might be determined by fetal size during the first 12 weeks after conception (Bukowski et al 2007). …”