Termination of Pregnancy and Its Consequences on Subsequent Birth Outcomes: A nationwide register-based study in Finland

Termination of pregnancy (TOP) is one of the most common gynaecological procedures performed among women. Around 7600 TOPs were performed in Finland in 2021. In recent decades, medical methods have almost replaced the traditional surgical methods in performing TOPs. Women undergoing TOP are mostly in the onset of their reproductive life and they are likely to become pregnant in later life. There has been a growing concern that TOP might lead to adverse birth outcomes in subsequent birth as regards the method and gestational age at TOP. However, existing studies on adverse birth outcomes after previous TOP and risk factors influencing repeat TOPs have been limited and results are partly inconsistent.

The aim of this study was to investigate the effects of prior TOP on subsequent birth outcomes such as preterm birth, low birth weight, perinatal death and small for gestational age (SGA) according to the TOP method, number of TOPs and gestational age at TOP. The study also assessed the factors influencing the risk of repeat TOPs.

This study includes four sub-studies, which are nationwide register-based studies. Sub- studies I, II and III include all first-time mothers with singleton birth (n=419 879) since 1996-2013 using the linked dataset of the Finnish Medical Birth Register and the Finnish Register of Induced Abortions. The sub-study IV includes women having had TOPs during 1987-2015 (n=193 741) and were identified using the Register of Induced Abortions.

Sub-study I showed increased risk of preterm birth and low birth weight among mothers with prior surgical TOP compared to the mothers with prior medical TOP. When compared with women with no prior TOP, a borderline increased risk for SGA birth was noted among mothers with surgical TOP. Sub-study II could not find any difference in risk of adverse birth outcomes except a marginal increased risk for SGA among women having a surgical TOP compared to women with no TOP. Increased risk of extremely preterm birth was found in women with more than one surgical TOP compared to no TOP.

Sub-study III demonstrated that TOP performed in later gestation was significantly associated with extremely preterm birth, very preterm birth, very low birth weight and small for gestational age in the subsequent birth when compared to the outcomes of women with no prior TOP. The sub-study also reflected higher risks of adverse birth outcomes in the subsequent birth after late-performed TOP than after early performed TOP.

The sub-study IV found out that older age, semi-urban or rural residency, being married or cohabiting and using reliable contraception were protective factors for repeat TOPs, whereas being parous was a risk for repeat TOPs.

In summary, this study indicates that surgical procedure in previous TOP and late-performed TOP are linked with adverse birth outcomes in subsequent birth. Being older, married or cohabiting status and using reliable method of contraception are protective factors for repeat TOPs, whereas being parous is a risk for repeat TOPs. Proper counselling should be provided to women seeking TOP including information on the possible health effects of TOP on subsequent births and the consequences of repeat TOPs. Similarly, initiation of reliable contraception particularly LARC, should be encouraged at the time of TOP to women having had TOP to reduce the number of repeat TOPs.