Maternal weight gain: a determinant for fetal abdominal circumference in the second trimester

To study the association between maternal weight gain in pregnancy and fetal abdominal circumference in the second trimester.

Prospective cross-sectional study.

Low-risk antenatal clinic.

Six hundred and fifty women with low-risk pregnancy.

Women with a regular menstrual period (28±4 days) and certain information on the last menstrual period were recruited when they were referred for routine ultrasound scanning. Women with a discrepancy of>14 days between ultrasound and menstrual age were excluded. Maternal weight gain during pregnancy was derived from information in the antenatal chart and the weekly weight gain was calculated. Fetal abdominal circumference measurements were registered in gestational weeks 15-25 and their z-scores, together with the z-scores of maternal weight gain, were used in a linear regression analysis. Main outcome measures. Association between maternal weight gain and fetal abdominal circumference.

Based on the complete data of 515 women we found a mean maternal weight gain during pregnancy of 0.39 kg/week and a positive association between this weight gain and fetal abdominal circumference in the second trimester (r=0.122 (95%CI 0.051-0.194)), with the strongest effect in women with the slowest weight gain (<0.28 kg/week) (r=0.554 (95%CI 0.261-0.846)).

Maternal weight gain in pregnancy is related to and may determine fetal abdominal circumference in gestational weeks 15-25, particularly in those women with a slow weight gain.