Balchin I

Maternal and Fetal Characteristics Associated With Meconium-Stained Amniotic Fluid

OBJECTIVE: To estimate the rates of meconium-stained amniotic fluid (AF) and adverse outcome in relation to gestational age and racial group, and to investigate the predictors of meconium-stained AF. METHODS: We studied 499,096 singleton births weighing at least 500 g, at 24 or more weeks of gestation, from 1988 to 2000. The predictors of meconium-stained AF from 37 weeks of gestation onward were determined using multiple logistic regression. RESULTS: The crude meconium-stained AF rates in preterm, term, and postterm births were 5.1% (95% confidence interval [CI] 4.9–5.4), 16.5% (95% CI 16.4–16.6), and 27.1% (95% CI 26.5–27.6), respectively; the rates in blacks, South Asians, and whites were 22.6% (95% CI 22.2–23.1), 16.8% (95% CI 16.5–17.1), and 15.7% (95% CI 15.6–15.8), respectively. Independent predictors of meconium-stained AF included being black (odds ratio [OR] 8.4, 95% CI 2.4–28.8), vaginal breech delivery (OR 4.7, 95% CI 4.2–5.3), being South Asian (OR 3.3, 95% CI 1.3–8.3), and being in an advancing week of gestation (OR 1.39, 95% CI 1.38–1.40). More blacks (17.9%, 95% CI 17.3–18.4) and South Asians (11.8%, 95% CI 11.5–12.1) with good outcome and no risk factors for fetal hypoxia had meconium-stained AF than did whites (11.2%, 95% CI 11.1–11.4). Using white neonates born at 40 weeks as reference, the absolute risk of adverse outcome at 41 and 42 weeks were 2% and 5% in whites, 3% and 7%, in South Asians, and 7% and 11% in blacks. CONCLUSION: Meconium-stained AF rates are different among races and across gestational age, and overall risk of adverse outcomes in meconium stained AF is low. LEVEL OF EVIDENCE: II

Timing of planned cesarean delivery by racial group.

OBJECTIVE: To estimate the incidence of newborn respiratory distress syndrome (RDS) and transient tachypnea of the newborn (TTN) in relation to gestational age and planned cesarean delivery in white, South Asian, and black women. METHODS: Included in this study were 442,596 white, South Asian, and black women who delivered single live infants at 28 of weeks gestation onwards between 1988 and 2000. Using multiple logistic regression, the gestation-specific patterns of RDS for all deliveries and RDS plus TTN for deliveries by planned cesarean delivery were analyzed by racial group. The predictors of RDS from 37 weeks of gestation onwards were determined. RESULTS: More South Asians (28.2%, 95% confidence interval [CI] 27.8–28.6) and blacks (24.6%, 95% CI 24.0–25.1) delivered spontaneously before 39 weeks than whites (16.9%, 95% CI 16.8–17.1). Respiratory distress syndrome patterns by gestation differed significantly (P<.001). Compared with whites, the gestation-specific crude RDS rate was lower in South Asians up until 40 weeks and after adjusting for confounders; South Asians were most protected against RDS (odds ratio [OR] 0.6, 95% CI 0.5–0.9). The gestation-specific patterns of RDS plus TTN after planned cesarean delivery also differed significantly (P<.001) between racial groups. The lowest rate of TTN plus RDS was at 40 weeks for whites, but in South Asians and blacks, it was lowest at 38 weeks. CONCLUSION: The gestation-specific patterns of RDS differed significantly by racial group from 32 weeks of gestation onwards. Preterm black infants had a lower rate of RDS when compared with whites; also, South Asians had the lowest rate of transient tachypnea until 38 weeks and the lowest rate of RDS until 40 weeks of gestation. The advantages of waiting until 39 weeks to perform planned cesarean delivery for white women are not seen in South Asians or blacks. LEVEL OF EVIDENCE: II

The effect of exclusion of cases with unrecorded best estimate of gestational age on the estimates of preterm birth rate

Objectives  To investigate the effect of excluding cases with unrecorded best estimate of gestational age at birth on pregnancy outcome reporting and to determine the reasons for unrecorded gestational age data.