Pregnancy intervals after stillbirth, neonatal death and spontaneous abortion and the risk of an adverse outcome in the next pregnancy in rural Bangladesh

Background: Studies have revealed associations between preceding short and long birth-to-birth or birth-to-pregnancy intervals and poor pregnancy outcomes. Most of these studies, however, have examined the effect of intervals that began with live births. Using data from Bangladesh, we examined the effect of inter-outcome intervals (IOI) starting with a non-live birth or neonatal death, on outcomes in the next pregnancy. Pregnancy spacing behaviors in rural northeast Bangladesh have changed little since 2004. Methods: We analyzed pregnancy histories for married women aged 15-49 years who had outcomes between 2000 and 2006 in Sylhet, Bangladesh. We examined the effects of the preceding outcome and the IOI length on the risk of stillbirth, neonatal death and spontaneous abortion using multinomial logistic regression models. Results: Data included 64,897 pregnancy outcomes from 33,495 mothers. Inter-outcome intervals of 27-50 months and live births were baseline comparators. Stillbirths followed by IOI's <=6 months, 7-14 months or overall <=14 months had increased risks for spontaneous abortion with adjusted relative risk ratios (aRRR) and 95% confidence intervals = 29.6 (8.09, 108.26), 1.84 (0.84, 4.02) and 2.53 (1.19, 5.36), respectively. Stillbirths followed by IOIs 7-14 months had aRRR 2.00 (1.39, 2.88) for stillbirths. Neonatal deaths followed by IOIs <=6 months had aRRR 28.2 (8.59, 92.63) for spontaneous abortion. Neonatal deaths followed by IOIs 7-14 and 15-26 months had aRRRs 3.08 (1.82, 5.22) and 2.32 (1.38, 3.91), respectively, for stillbirths; and aRRRs 2.81 (2.06, 3.84) and 1.70 (1.24, 3.84), respectively, for neonatal deaths. Spontaneous abortions followed by IOIs <=6 months and 7-14 months had, respectively, aRRRs 23.21 (10.34, 52.13) and 1.80 (0.98, 3.33) for spontaneous abortion. Conclusion: In rural northeast Bangladesh, short inter-outcome intervals after stillbirth, neonatal death and spontaneous abortion were associated with a high risk of a similar outcome in the next pregnancy. These findings are aligned with other studies from Bangladesh. Two studies from similar settings have found benefits of waiting six months before conceiving again, suggesting that incorporating this advice into programs should be considered. Further research is warranted to confirm these findings.