羊水粪染与孕周及新生儿酸碱平衡状态

OBJECTIVE: To estimate whether the acid-base status of neonates born to women with meconium-stained amniotic fluid varies across gestation. METHODS: We carried out a retrospective cohort study of all pregnancies that were complicated by meconium-stained amniotic fluid in 2004. Cases were identified from a perinatal pathology database that contained data on all pregnancies complicated by meconium- stained amniotic fluid. Data abstracted from the charts included gestational age at delivery, umbilical arterial pH, birth weight, and the presence or absence of labor. Cases were stratified according to gestational age at delivery. The distribution of meconium-stained amniotic fluid across gestation was computed. The mean umbilical arterial pH values (with 95% confidence intervals) across gestation were assessed by analysis of variance. RESULTS: The mean umbilical arterial pH in women with meconium-stained amniotic fluid did not differ across gestation. The overall incidence of meconium-stained amniotic fluid was 12.0% (766 of 6,403 deliveries). The rates of meconium-stained amniotic fluid increased from 1.2% at 32 weeks to 100% at 42 weeks. CONCLUSION: The rising incidence of meconium-stained amniotic fluid with gestational age is consistent with the hypothesis that fetal maturation is a major etiologic factor in meconium passage. Also, the lack of variation of mean umbilical arterial pH across gestation suggests that fetal acidemia is not increased when meconium passage occurs earlier in pregnancy rather than at later gestational ages.

胎盘早剥的危险因素:早产胎膜早破、子宫内感染和羊水过少

OBJECTIVE: To examine whether preterm premature rupture of membranes (PROM), intrauterine infection, and oligohydramnios are risk factors for placental abruption. METHODS: Data for this retrospective cohort study were derived from the 1988 National Maternal and Infant Health Survey (N=11,777). Association between abruption and these clinical risk factors was expressed as relative risk (RR) and 95%confidence interval (CI), with multivariate adjustment for potential confounders. RESULTS: The overall incidence of abruption was 0.87%. The risk of abruption was 3.58-fold higher (95%CI 1.74-7.39)among women with preterm PROM (2.29%) compared with women with intact membranes (0.86%). The rates of abruption among women with and without intrauterine infection were 4.81%and 0.83%, respectively (RR 9.71, 95%CI 3.23-29.17). However, oligohydramnios was not associated with abruption (1.46%compared with 0.87%; RR 2.09, 95%CI 0.92-5.31). Compared with women with intact membranes, the RR for abruption among preterm PROM and whose membranes were ruptured for 24-47 hours and 48 hours or more before delivery, respectively, were 2.37 (95%CI 0.99-9.09), and 9.87 (95%CI 3.57-27.82). When preterm PROM was accompanied by intrauterine infections, the RR for abruption was 9.03 (95%CI 2.80-29.15) compared with women with intact membranes and no infections. Similarly, preterm PROM accompanied by oligohydramnios conferred over a 7.17-fold risk (95%CI 1.35-38.10) for abruption compared with women with neither of these 2 conditions. CONCLUSION: Women presenting with preterm PROM are at increased risk of developing abruption, with the risk being higher either in the presence of intrauterine infections or oligohydramnios. Physicians managing patients with preterm PROM should be aware that these patients are at increased risk of developing abruption after 24 hours following preterm PROM.

妊娠期母体血管反应性的无创超声评估:一项纵向研究

OBJECTIVE: To estimate the pattern of maternal vascular reactivity in normal a nd high-risk pregnancies using postocclusion brachial artery diameter. METHODS: Prospective, longitudinal study of 44 low-risk singleton pregnancies and 28 hi gh-risk pregnancies, defined as pregestational diabetes (n = 7), chronic hypert ension (n = 4), twin gestation (n = 6), and a previous history of preeclampsia, fetal growth restriction, or vascular disease (n = 11). During each trimester, t he brachial artery was ultrasonographically imaged above the antecubital crease. Brachial artery diameter was measured and then occluded for 5 minutes using an inflated blood pressure cuff. Changes in brachial artery diameter at 1 minute af ter occlusion were expressed as percent change from baseline and were compared a cross trimesters for both low-risk and high-risk groups, adjusting for potenti al confounders. RESULTS: Brachial artery diameters were increased after occlusio n in every trimester for all groups. For low-risk women, the degree of postoccl usion brachial artery dilatation was similar in the first and second trimesters, but was lower in the third trimester. In the first trimester, low-risk women h ad significantly greater brachial artery diameter increases at 1 minute compared with high-risk singleton pregnancies (19%compared with 12%; P < .001). Compa red with low-risk women, pregnancies complicated by pregestational diabetes or chronic hypertension had significantly smaller 1-minute brachial artery diamete r changes in the first trimester (7.0 ±0.5%, P < .001), whereas twin gestation s had greater brachial artery responses (22.9 ±6.0%, P < .001). Women with pre vious preeclampsia or vascular disease had responses similar to low-risk women. CONCLUSION: Maternal vascular reactivity as assessed by postocclusion brachial artery dilatation decreases in the third trimester in both low-risk and high-r isk women. In addition, singleton pregnancies at high risk for preeclampsia disp lay decreased brachial artery reactivity compared with low-risk women.

不同程度的新生儿体重异常情况下分娩方式对美国双胞胎新生儿死亡率的影响

The purpose of this study was to examine if neonatal mortality rates (NMR) based on birth weight discordance (BWD) differ based on mode of delivery. The population- based US “ matched multiple birth" database (1995 to 1998) was used to examine the effect of vaginal/vaginal (VV) and cesarean/cesarean (CC)- modes of delivery (MOD) on neonatal mortality (< 28 days after birth). Births at < 32 weeks, congenital malformations, chromosomal anomalies, and discordant MOD (vaginal/cesar- ean) were excluded. The association between MOD (with CC as the reference) and neonatal mortality was expressed as relative risks (RR) with 95% CI, derived from logistic regression models. The NMR increased with increasing degrees of BWD regardless of mode of delivery. CC was associated with decreased NMR when BWD was between 20% and 40% , but this reached significance at BWD ≥ 40% ; VV pairs had a 1.6- fold (95% CI 1.1- 2.2) increased NMR compared with CC. In twins with BWD < 40% , MOD has no effect on NMR. Beyond or equal to 40% discordance, there was lower NMR with cesar- ean- cesarean delivery.