RESEARCH – March 2014

Singleton IVF children in Estonia: possible health determinants,perinatal mortality risk and maternal socio-demographic background

Authors: Kärt Allvee, Helle Karro, Kaja Rahu

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Aim. To assess the perinatal outcome of Estonian IVFchildren and to describe their mothers’ socio-demographic background.

Methods. The retrospective register-based study is based on the children born in Estonia between 2001 and 2009. Data were obtained from the Estonian Medical Birth Registry. It contains information on maternal socioeconomic background and on infant outcomes until the age of 7 days. Data of live- and stillbirths were gathered from all health institutions providing maternity care service in Estonia. Every newborn is given a unique personal identification number.

The cohort of children who were born as a result of IVF (743 primipara singletons) was compared with a cohort of naturally conceived children (27 547 primipara singletons). The odds ratios (OR) for mother’s socioeconomic background, perinatal outcomes, mode of delivery and perinatal death were calculated using logistic regression models. The difference in mean birthweight was estimated using a linear regression model. The 95% confidence interval (CI) was calculated for each measure.

Results. The mothers of the IVF infants were more likely 35-years-old or older (adjusted OR=6.54; 95% CI 5.52−7.73), married, with secondary or secondary special education, Estonians by ethnicity. The IVF children had greater odds of being born by Cesarean section (adjusted OR=2.03; 95% CI 1.74−2.37). They were more likely preterm (adjusted OR=1.50; 95% CI 1.14−1.99), or very preterm (adjusted OR=2.33; 95% CI 1.38−3.91). The risk for low birth weight among the IVF infants was statistically significantly increased (adjusted OR=1.74; 95% CI 1.28−2.37). The difference in mean birth weight between the IVF and the control cohort was 47 g (95% CI 7−86 g): the IVFinfants were lighter compared with the control infants. Perinatal mortality risk was not higher in the cohort of the IVF infants. The effect of maternal age (35–44 vs. 25–34 years) on perinatal mortality risk (OR= 2.12; 95% CI 1.36–3.30) was statistically significant.

Conclusions. The results of the analysis confirm previous evidence that preterm, very preterm and low birthweight babies were more common in the IVF cohort than in the control cohort. The IVF infants were more often born by Cesarean section and their mothers were older and more likely married.