This systematic review of 58 observational studies identified hypothetical causal mechanisms explaining the effects of short and long intervals between pregnancies on maternal, perinatal, infant, and child health, and critically examined the scientific evidence for each causal mechanism hypothesized. The following hypothetical causal mechanisms for explaining the association between short intervals and adverse outcomes were identified: maternal nutritional depletion, folate depletion, cervical insufficiency, vertical transmission of infections, suboptimal lactation related to breastfeeding-pregnancy overlap, sibling competition, transmission of infectious diseases among siblings, incomplete healing of uterine scar from previous cesarean delivery, and abnormal remodeling of endometrial blood vessels. Women's physiological regression is the only hypothetical causal mechanism that has been proposed to explain the association between long intervals and adverse outcomes. We found growing evidence supporting most of these hypotheses.
In Latin America, interpregnancy intervals shorter than 12 months and longer than 59 months are independently associated with increased risk of adverse perinatal outcomes. These data suggest that spacing pregnancies appropriately could prevent perinatal deaths and other adverse perinatal outcomes in the developing world.
Post-abortion interpregnancy interval (PAII): the time elapsed between the day of the abortion and the first day of the last menstrual period for the index pregnancy.
OBJECTIVE
To evaluate the efficacy and safety of prophylactic misoprostol use at cesarean delivery for reducing intraoperative and postoperative hemorrhage.
STUDY DESIGN
Systematic review and meta-analysis of randomized controlled trials.
RESULTS
Seventeen studies (3174 women) were included of which 7 evaluated misoprostol versus oxytocin and 8 evaluated misoprostol plus oxytocin versus oxytocin. Overall, there were no significant differences in intraoperative and postoperative hemorrhage between sublingual or oral misoprostol and oxytocin. Rectal misoprostol, compared with oxytocin, was associated with a significant reduction in intraoperative and postoperative hemorrhage. The combined use of sublingual misoprostol and oxytocin, compared with the use of oxytocin alone, was associated with a significant reduction in the mean decrease in hematocrit (mean difference, −2.1%; 95% confidence interval [CI], −3.4 to −0.8) and use of additional uterotonic agents (relative risk, 0.33; 95% CI, 0.18-0.62). Compared with oxytocin alone, buccal misoprostol plus oxytocin reduced the use of additional uterotonic agents; rectal misoprostol plus oxytocin decreased intraoperative and postoperative blood loss, mean fall in hematocrit, and use of additional uterotonic agents; and intrauterine misoprostol plus oxytocin reduced the mean fall in hemoglobin and hematocrit. Women receiving misoprostol, alone or combined with oxytocin, had a higher risk of shivering and pyrexia.
CONCLUSION
Misoprostol combined with oxytocin appears to be more effective than oxytocin alone in reducing intraoperative and postoperative hemorrhage during caesarean section. There were no significant differences in intraoperative and postoperative hemorrhage when misoprostol was compared to oxytocin. However, these findings were based on a few trials with methodological limitations.
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