Interpregnancy Interval and Adverse Perinatal Outcomes: A Record-Linkage Study Using the Manitoba Population Research Data Repository.

To examine the association between the interpregnancy interval (IPI) and preterm birth, low birth weight, and SGA birth in a developed country with universal health coverage. We conducted a secondary analysis of data housed at the Manitoba Centre for Health Policy. All live births in Manitoba hospitals over a 29-year period were identified and consecutive births to the same mother were grouped into sibling pairs to calculate the IPI for the younger siblings. Logistic regression models were fit to examine the association between the IPI and adverse perinatal outcomes, adjusted for potentially confounding sociodemographic and clinical factors. In a cohort of more than 171 000 births and relative to IPIs of 18 to 23 months, IPIs shorter than 12 and longer than 23 months were associated with significantly increased odds of preterm birth overall and both medically indicated and spontaneous preterm births, low birth weight, and SGA birth. The strongest association observed was for intervals shorter than 6 months and spontaneous preterm birth (adjusted OR 1.83, 95% CI 1.65-2.03). When the outcome was modelled as GA categories, the strongest association observed was for intervals shorter than 6 months and early preterm birth (<34 weeks' GA; adjusted OR 2.47, 95% CI 2.07-2.94). If the associations observed between the IPI and adverse perinatal outcomes in this large, population-based cohort are causal, birth spacing could form an important target of public health messaging in Canada.

Coo H ，Brownell MD ，Ruth C ，Flavin M ，Au W ，Day AG ... -  《-》

Interpregnancy Interval and Congenital Anomalies: A Record-Linkage Study Using the Manitoba Population Research Data Repository.

Congenital anomalies are a serious public health issue, and relatively few modifiable risk factors have been identified. Our objective was to investigate one such potential risk factor, the interpregnancy interval (IPI). We conducted a secondary analysis of data housed at the Manitoba Centre for Health Policy. In-hospital live births and stillbirths of at least 20 weeks' gestation were identified, and consecutive births to the same mother were grouped into sibling pairs to calculate the IPI for the younger siblings of each pair. Logistic regression models were fit to examine the association between the IPI and any congenital anomaly, as well as CNS and chromosomal anomalies, while controlling for potentially confounding sociodemographic and clinical factors. Among 172 909 live births and stillbirths, the IPI was not significantly associated with congenital anomalies overall or with chromosomal anomalies. Short IPIs were associated with significantly increased odds of CNS anomalies relative to IPIs of 18-23 months (adjusted OR [aOR] for IPIs <6 months 2.15; 95% CI 1.48-3.12), whereas the aOR for IPIs ≥60 months was elevated but not statistically significant (aOR 1.50; 95% CI 0.96-2.34). In a sensitivity analysis in which the cohort was restricted to births from 2003 onwards (which yielded more complete data on health-related behaviours), the observed effect for IPIs shorter than 6 months and CNS anomalies was attenuated and no longer significant, but it remained elevated (aOR 1.65; 95% CI 0.85-3.24). The findings for CNS anomalies warrant further investigation.

Coo H ，Brownell MD ，Ruth C ，Flavin M ，Au W ，Day AG ... -  《-》

Within-Family Analysis of Interpregnancy Interval and Adverse Birth Outcomes.

Class QA ，Rickert ME ，Oberg AS ，Sujan AC ，Almqvist C ，Larsson H ，Lichtenstein P ，D'Onofrio BM ... -  《-》

Effect of Interpregnancy Interval on Adverse Perinatal Outcomes in Southern China: A Retrospective Cohort Study, 2000-2015.

In January 2016, a universal two-child policy was introduced in China. The association of interpregnancy interval (IPI) with perinatal outcomes has not previously been assessed among Chinese population. We investigated the effect of IPI after live birth on the risks of preterm delivery, and small, and large for gestational age births in China. We conducted a cohort study among 227 352 Chinese women with their first and second delivery during 2000 to 2015. IPI was calculated as months from first live delivery to conception of the second pregnancy. Poisson regression models with robust variance were fit to evaluate associations of IPI with risk of adverse perinatal outcomes, adjusted for potential confounders. Compared to IPI of 24- <30 months, IPI <18 months was associated with higher risks of preterm birth (PTB) and small for gestational age (SGA). For IPI <6 months, the adjusted relative risks (RR) for PTB and SGA were 2.04 (95% confidence interval [CI] 1.83, 2.27) and 1.43 (95% CI 1.31, 1.57), respectively. Women with IPI ≥60 months had higher risks of PTB and large for gestational age (LGA). For IPI ≥120 months, the adjusted RRs for PTB and LGA were 1.67 (95% CI 1.43, 1.94) and 1.10 (95% CI 0.97, 1.26). Women with IPI <18 months after live birth had higher risk of PTB and SGA, and IPI ≥60 months was associated with higher risk of PTB and LGA. These findings may provide information to Chinese couples about the appropriate interpregnancy interval for a second pregnancy.

Zhang L ，Shen S ，He J ，Chan F ，Lu J ，Li W ，Wang P ，Lam KBH ，Mol BWJ ，Yeung SLA ，Xia H ，Schooling CM ，Qiu X ... -  《-》

Interpregnancy Intervals in a Contemporary Manitoba Cohort: Prevalence of So-Called Suboptimal Intervals and Associated Maternal Characteristics.

Short and long interpregnancy intervals (IPIs) have been associated with various adverse outcomes, and a 2016 American College of Obstetricians and Gynecologists' Committee Opinion recommends an optimal IPI of 18 months to 5 years. Descriptive data on the IPI in Canada are lacking. The objective of this study was to examine IPIs in a Manitoba cohort. The study analyzed a subset of records from a larger dataset used to examine the IPI and adverse perinatal outcomes. For that study, Manitoba's Hospital Abstracts data were searched to identify births from 1985 to 2014. Each two consecutive live births to the same mother formed a sibling pair. The IPI was calculated as the interval between the two siblings' births, minus the younger sibling's GA. Information on maternal characteristics was extracted from various datasets housed in the Manitoba Population Research Data Repository. The current analysis examined second and higher-order births between 2010 and 2014. The proportion of suboptimal IPIs was determined and IPIs were cross-tabulated with birth year and maternal subgroups. More than half of pregnancies were conceived following a suboptimal interval. IPIs of less than 6 months - which have been associated with the highest risk of adverse outcomes - were more prevalent among certain subgroups. These included younger women as well as women who received inadequate prenatal care, smoked or drank alcohol during pregnancy, were low income, or did not graduate from high school. Suboptimal IPIs were common in this Manitoba cohort. Stakeholders should consider whether greater efforts to promote appropriate birth spacing are warranted.

Coo H ，Brownell MD ，Ruth C ，Flavin M ，Au W ，Day AG ... -  《-》