scholarly journals 455Association of interpregnancy interval and preterm births: what does a sibling-matched study indicate?

2021 ◽  
Vol 50 (Supplement_1) ◽  
Author(s):  
Gizachew Tessema ◽  
M Luke Marinovich ◽  
Siri E Håberg ◽  
Mika Gissler ◽  
Jonathan A Mayo ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Birth Outcomes ◽  
Meta Analysis ◽  
Conditional Logistic Regression ◽  
Preterm Births ◽  
Adverse Birth Outcomes ◽  
Interpregnancy Interval ◽  
Insufficient Evidence ◽  
Increased Risk ◽  
Matched Study

Abstract Background Most evidence for interpregnancy interval (IPI) and adverse birth outcomes come from between-women (unmatched) studies that are prone to incomplete control for confounders that vary between women. Comparing pregnancies to the same women (sibling-matched) can address this issue. Methods We conducted an international longitudinal study of births from Australia, Finland, Norway, and United States (California) covering over three decades (1980-2017). We included 5,523,914 births to 3,849,737 women, and within each country, we first investigated the associations between IPI and preterm birth (PTB), spontaneous PTB using logistic regression (unmatched analyses). Second, we used conditional logistic regression comparing IPIs in the same women (sibling-matched analyses), with 2,908,907 births to 1,234,730 women having at least two IPIs. Random effects meta-analysis was used to calculate pooled effect estimates. Results Compared to an IPI of 18-23 months, there was insufficient evidence of association between IPI <6 months and overall PTB (adjusted odds ratio (aOR)=1.08, 95%CI 0.99-1.18) but increased odds of spontaneous PTB (aOR=1.38, 95%CI 1.21-1.57). We observed elevated odds of both birth outcomes associated with IPI ≥60 months. In comparison, between-women analyses showed elevated odds of adverse birth outcomes for <12 month and >24 month IPIs. Conclusions We found consistently elevated odds of PTB following long IPIs. IPI shorter than 6 months were associated with elevated risk of spontaneous PTB, but there was insufficient evidence for increased risk of overall PTB. Key message Current recommendations of waiting at least 24 months to conceive after a previous pregnancy, may be unnecessarily long in high-income countries.

scholarly journals Interpregnancy intervals and adverse birth outcomes in high-income countries: An international cohort study

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0255000
Author(s):  
Gizachew A. Tessema ◽  
M. Luke Marinovich ◽  
Siri E. Håberg ◽  
Mika Gissler ◽  
Jonathan A. Mayo ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Cohort Study ◽  
Birth Outcomes ◽  
Meta Analysis ◽  
Conditional Logistic Regression ◽  
The United States ◽  
High Income ◽  
Adverse Birth Outcomes ◽  
Insufficient Evidence ◽  
Increased Risk

Background Most evidence for interpregnancy interval (IPI) and adverse birth outcomes come from studies that are prone to incomplete control for confounders that vary between women. Comparing pregnancies to the same women can address this issue. Methods We conducted an international longitudinal cohort study of 5,521,211 births to 3,849,193 women from Australia (1980–2016), Finland (1987–2017), Norway (1980–2016) and the United States (California) (1991–2012). IPI was calculated based on the time difference between two dates—the date of birth of the first pregnancy and the date of conception of the next (index) pregnancy. We estimated associations between IPI and preterm birth (PTB), spontaneous PTB, and small-for-gestational age births (SGA) using logistic regression (between-women analyses). We also used conditional logistic regression comparing IPIs and birth outcomes in the same women (within-women analyses). Random effects meta-analysis was used to calculate pooled adjusted odds ratios (aOR). Results Compared to an IPI of 18–23 months, there was insufficient evidence for an association between IPI <6 months and overall PTB (aOR 1.08, 95% CI 0.99–1.18) and SGA (aOR 0.99, 95% CI 0.81–1.19), but increased odds of spontaneous PTB (aOR 1.38, 95% CI 1.21–1.57) in the within-women analysis. We observed elevated odds of all birth outcomes associated with IPI ≥60 months. In comparison, between-women analyses showed elevated odds of adverse birth outcomes for <12 month and >24 month IPIs. Conclusions We found consistently elevated odds of adverse birth outcomes following long IPIs. IPI shorter than 6 months were associated with elevated risk of spontaneous PTB, but there was insufficient evidence for increased risk of other adverse birth outcomes. Current recommendations of waiting at least 24 months to conceive after a previous pregnancy, may be unnecessarily long in high-income countries.

scholarly journals 748Misclassification of interpregnancy interval attributable to miscarriages/induced abortions: quantifying its impact on preterm births

2021 ◽  
Vol 50 (Supplement_1) ◽  
Author(s):  
Gizachew Tessema ◽  
Siri E Håberg ◽  
Gavin Pereira ◽  
Maria C Magnus
Keyword(s):  
Regression Analysis ◽  
General Practitioner ◽  
Birth Outcomes ◽  
Preterm Births ◽  
The Other ◽  
Adverse Birth Outcomes ◽  
Interpregnancy Interval ◽  
Relative Risks ◽  
Binomial Regression ◽  
Induced Abortions

Abstract Background A paucity of studies explored how intervening pregnancy events (miscarriages and induced abortions) contribute to interpregnancy interval (IPI) misclassification and whether this misclassification translates into bias in the estimated effect of IPI on adverse birth outcomes. Methods We included identified three national registries (Birth Register, the General Practitioner, and Patient Register) to obtain information on registered pregnancies (n = 167,012), with at least two consecutive pregnancies per mother, occurring between 2008 and 2016 in Norway. We computed two IPIs, one that accounted only two consecutive pregnancies ending after 20 weeks of gestation (standard IPI definition) and the other that accounted two consecutive pregnancies with various outcomes including miscarriages/induced abortions (corrected IPI definition). We independently assessed the association between the two IPIs and preterm births (PTB). Log binomial regression analysis was conducted. Relative risks (aOR) and 95% confidence interval (CI) were estimated. Results In the study, 4.7% of births were PTB. While 11.7% of pregnancies occurred &lt;6 months in the corrected IPI definition, the proportion reduced to 4.4% in the standard IPI definition, with over 60% of IPIs were misclassified. After adjusting for confounders, there was a modest overestimation of risk of PTB for pregnancies following short IPI (&lt;6 months) (RR = 1.76, 95% CI: 1.60-1.95) for the standard IPI definition as compared to the risk of PTB (RR = 1.52, 95% CI: 1.41-1.65) following short IPI in the corrected IPI definition. Conclusions There was a significant misclassification bias associated with miscarriages/induced abortions which should not be ignored when assessing the effect of IPI on PTB.

Re-evaluation of Link Between Interpregnancy Interval and Adverse Birth Outcomes

2014 ◽  
Vol 69 (12) ◽  
pp. 717-719
Author(s):  
Stephen J. Ball ◽  
Gavin Pereira ◽  
Peter Jacoby ◽  
Nicholas de Klerk ◽  
Fiona J. Stanley
Keyword(s):  
Birth Outcomes ◽  
Adverse Birth Outcomes ◽  
Interpregnancy Interval

scholarly journals Paternal age and the risk of low birth weight and preterm delivery: a Finnish register-based study

2018 ◽  
Vol 72 (12) ◽  
pp. 1104-1109 ◽  
Author(s):  
Alice Goisis ◽  
Hanna Remes ◽  
Kieron Barclay ◽  
Pekka Martikainen ◽  
Mikko Myrskylä
Keyword(s):  
Birth Weight ◽  
Low Birth Weight ◽  
Preterm Delivery ◽  
Birth Outcomes ◽  
Conclusive Evidence ◽  
Paternal Age ◽  
Adverse Birth Outcomes ◽  
Maternal Characteristics ◽  
Parental Characteristics ◽  
Increased Risk

BackgroundBased on existing studies, there is no conclusive evidence as to whether and why paternal age matters for birth outcomes.MethodsWe used Finnish population registers on 106 652 children born 1987–2000. We first document the unadjusted association between paternal age and the risk of low birth weight (LBW; <2500 g) and preterm birth (<37 weeks’ gestation). Second, we investigate whether the unadjusted association is attenuated on adjustment for child’s, maternal and parental socioeconomic characteristics. Third, by adopting a within-family design which involves comparing children born to the same father at different ages, we additionally adjust for unobserved parental characteristics shared between siblings.ResultsThe unadjusted results show that being born to a father aged 40+, as opposed to a father aged 30–34, is associated with an increased risk of LBW of 0.96% (95% CI 0.5% to 1.3%) and to a younger father (<25) with a 1% (95% CI 0.6% to 1.3%) increased risk. The increased risk at younger paternal ages is halved on adjustment for the child’s characteristics and fully attenuated on adjustment for child/parental characteristics. The increased risk at paternal ages 40+ is partially attenuated on adjustment for maternal characteristics (β=0.62%; 95% CI 0.13% to 1.1%). Adjustment for unobserved parental characteristics shared by siblings further attenuates the 40+ coefficient (β=0.4%; 95% CI −0.5% to −1.2%). Results for preterm delivery are similar.ConclusionsThe results underscore the importance of considering paternal age as a potential risk factor for adverse birth outcomes and of expanding research on its role and the mechanisms linking it to birth outcomes.

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