Determinants of perinatal mortality and serious neonatal morbidity in the second twin.

OBJECTIVE: To identify potential determinants of perinatal mortality and neonatal morbidity among second twins relative to first twins. METHODS: A retrospective cohort design was used to study twin deliveries in Nova Scotia from 1988 to 2002. Monoamniotic or conjoined twins and twin pairs with major congenital anomaly or antepartum fetal death of either twin were excluded. The primary outcome was a composite measure of perinatal mortality and neonatal morbidity, including birth asphyxia, respiratory distress, neonatal trauma, and infection. Risk of adverse outcome of second twins relative to first-born co-twins was determined by matched-pair analysis. RESULTS: Of 1,542 twin pairs, the second twin was at greater risk of composite adverse outcome (relative risk [RR] 1.62, 95% confidence interval [CI] 1.38-1.9) than the first twin. This excess risk was evident independent of presentation, chorionicity, or infant sex but was associated with planned vaginal delivery, birth weight discordance, and prolonged interdelivery interval. Term second twins were less likely to suffer excess morbidity with elective cesarean (RR 1.0, 95% CI 0.14-7.10) than with planned vaginal delivery (RR 3.0, 95% CI 1.47-6.11). The major contributors to neonatal morbidity in the second twin were birth asphyxia at 37 weeks or later and respiratory distress syndrome at less than 37 weeks. CONCLUSION: The second twin is at greater risk of adverse perinatal outcome than the first twin, independent of presentation, chorionicity, or infant sex. Planned vaginal delivery, birth weight discordance, and prolonged interdelivery interval increase this infant risk. Elective cesarean delivery at term may improve perinatal outcome for the second twin. However, the number of cesarean births required to prevent one case of composite adverse outcome, assuming causality, was 33.

A preliminary study of cutaneous blood flow associated with postpartum use of oral misoprostol.

OBJECTIVE: To evaluate cutaneous blood flow, as identified by Doppler fluximetry, to understand the etiology of shivering associated with the postpartum use of oral misoprostol. METHODS: Eligible participants were recruited from a group of women who were enrolled in an ongoing randomized trial comparing 400 microg of oral misoprostol to 5 IU of intravenous oxytocin for postpartum hemorrhage prophylaxis. The laser Doppler fluximeter was used to noninvasively measure changes in peripheral tissue perfusion (flux). A skin probe attached to the upper arm recorded flux and skin temperature. Baseline levels were obtained before delivery and for 30 minutes postpartum (maximum flux) after the women received the study drug. Continuous variables were analyzed with Student t-test or paired t-test, with the Wilcoxon signed rank test used for non-parametric ordinal data. Categoric data were analyzed with the chi-square test or Fisher's exact test. RESULTS: Sixteen women were enrolled, and 10 women had a vaginal delivery and received the study drugs. Among these 10 women, a significant difference between baseline and maximum flux levels was demonstrated for both women treated with oxytocin (P = .04) and for those treated with misoprostol (P = .04). Women treated with oxytocin also had a significant change in skin temperature (P = .04). Maximum flux levels were not significantly different between the women receiving misoprostol compared with those receiving oxytocin (P = .42). CONCLUSIONS: Shivering associated with oral misoprostol may not be due to a resetting of the hypothalamic thermoregulatory centre. Further study is needed to determine whether shivering associated with oral misoprostol is dose-dependent or related to locally mediated phenomena.

Incidence of open neural tube defects in Nova Scotia after folic acid fortification.

BACKGROUND: With the goal of preventing open neural tube defects (NTDs), recommendations for folic acid supplementation before conception were introduced in Canada in 1994, and by November 1998 Canadian grain products were being fortified with folic acid. We wished to determine whether the annual incidence of open NTDs in Nova Scotia, including those in stillbirths and terminated pregnancies, changed after the introduction of either folic acid supplementation or fortification. METHODS: For the 10-year period from Jan. 1, 1991, to Dec. 31, 2000, we retrospectively extracted the total number of births in Nova Scotia and the number of live births and stillbirths with open NTDs from the Nova Scotia Atlee Perinatal Database as well as the number of terminated pregnancies affected by NTDs from the Fetal Anomaly Database. We determined the total annual incidence of all open NTDs, and of the subgroups spina bifida and anencephaly, per 1000 births in the province during the periods before (1991-1994) and after (1995-1998) folic acid supplementation initiatives were begun but before folic acid fortification of grain products was implemented, and during the periods before (1991-1997) and after (1998-2000) fortification. RESULTS: In the period after supplementation initiatives were begun but before fortification was implemented, the incidence of open NTDs did not change significantly: the mean annual rate was 2.55 per 1000 births during 1991-1994 and 2.61 per 1000 births during 1995-1997 (relative risk [RR] 1.02, 95% confidence interval [CI] 0.77-1.35). After the fortification was implemented the incidence of open NTDs decreased by more than 50%: the mean annual rate was 2.58 per 1000 births during 1991-1997 and 1.17 per 1000 births during 1998-2000 (relative risk 0.46, 95% CI 0.32-0.66). INTERPRETATION: The recommendations for folic acid supplementation alone did not appear to succeed in reducing the incidence of open NTDs in Nova Scotia, whereas the fortification of grain products with folic acid did result in a significant reduction in the incidence.