Low maternal weight, failure to thrive in pregnancy, and adverse pregnancy outcomes

Objective The purpose of this study was to correlate low maternal pregravid weight, delivery weight, and poor gestational weight gain with perinatal outcomes. Study design Maternal and perinatal data from January 1997 to June 2001 were obtained from a perinatal database at MetroHealth Medical Center. Low maternal weight (LMW) was defined as pregravid or delivery weight <100 pounds or body mass index (BMI) ≤19.8 kg/m2. Low maternal weight gain was defined as <0.27 kg per week. Perinatal complication rates in these subjects were compared with those with weights of 100 to 200 pounds, normal BMI (>19.8, <26 kg/m2), and normal gestational weight gain (0.27-0.52 kg/wk). Chi-square and t tests were used where appropriate. P<.05 was significant. Results A percentage (2.6%) of 15,196 subjects began pregnancy weighing ≤100 pounds; 0.15% weighed <100 pounds at delivery and 13.2% had a pregravid BMI ≤19.8 kg/m2. Pregravid LMW was highly correlated with ethnicity (Asians, 8.6%; Hispanics, 4.3%; Caucasians, 2.5%; African Americans, 1.9%; P<.001). Subjects with pregravid LMW were at increased risk for intrauterine growth restriction (IUGR) (relative risk [RR], 2.3, 95% CI, 1.3-4.05), and perineal tears (3rd-degree lacerations; RR, 1.8, 95% CI, 1.1-2.9), and low birth weight ([LBW] <2500 g; RR, 1.8, 95% CI, 1.1-2.9). They had a lower risk of cesarean section (RR, 0.72, 95% CI, 0.56-0.92) and preterm delivery (PTD) (RR, 1.1, 95% CI, 0.97-1.06). Pregravid BMI <19.8 kg/m2 was associated with preterm labor (PTL) (RR, 1.22, 95% CI, 1.02-1.46), IUGR (RR, 1.67, 95% CI, 1.2-2.39), and LBW (<2500 g; RR, 1.13, 95% CI, 1.0-1.27) and was protective against cesarean delivery (RR, 0.8, 95% CI, 0.71-0.91). Delivery LMW was associated with LBW (<2500 g; RR, 2.81, 95% CI, 1.62-4.84), active-phase arrest (RR, 5.07, 95% CI, 1.85-13.9), PTL and PTD (RR, 2.5, 95% CI, 1.02-6.33, and RR, 2.45, 95% CI, 1.4-4.4, respectively), a lower gestational age at delivery (36.8 vs 38.3 wks, P<.05), and mediolateral episiotomy (RR, 9.6, 95% CI, 1.9-48.0). A percentage (0.8%) of subjects had BMI <19.8 kg/m2 at delivery. Low delivery BMI was associated with birth weight <2500 g (RR, 1.74, 95% CI, 1.3-2.32), PTL (RR, 2.16, 95% CI, 1.45-3.19), and PTD (RR, 1.57, 95% CI, 1.18-2.11). Failure to thrive in pregnancy (weight gain <0.27 kg/wk) was associated with LBW (<1500 g; RR, 1.23, 95% CI, 1.03-1.45), <2500 g; RR, 1.22, 95% CI, 1.13-1.33), and PTL and PTD (RR, 1.2, 95% CI, 1.05-1.37, and RR, 1.11, 95% CI, 1.02-1.2, respectively). Conclusion Low weight and BMI at conception or delivery, as well as poor weight gain during pregnancy, are associated with LBW, prematurity, and maternal delivery complications.