Association between history of fertility problems and pregnancy and birth complications: A longitudinal...

Infertility is a common reproductive health issue, associated with increased risks of pregnancy complications. However, shared underlying risk factors such as age, BMI, PCOS, endometriosis, and lifestyle may partly explain these associations. In a population-based cohort of women, this study aimed to determine whether a history of fertility problems is independently associated with adverse pregnancy and birth outcomes, including gestational diabetes, hypertensive disorders of pregnancy, low birthweight, and preterm birth.

This was a secondary analysis of data from the 1973 to 1978 cohort of the Australian Longitudinal Study on Women's Health, that included surveys from 2003 to 2018 (n = 9854). We examined associations between self-reported fertility problems and four adverse outcomes: gestational diabetes, hypertensive disorders of pregnancy, low birthweight, and preterm birth. Generalized estimating equations with an exchangeable correlation structure were used, with sequential adjustment for socio-demographic, health, and lifestyle-related characteristics.

Among 5653 women who reported a live birth, 897 (15.9%) reported a history of fertility problems, of whom 71.6% had sought help. After adjusting for socio-demographic factors alone, there was a statistically significant increased risk of adverse pregnancy outcomes for women with a history of fertility problems compared to those without. However, after further adjustment for health characteristics and pregnancy-related variables, the associations were no longer statistically significant: gestational diabetes [Relative risk (RR): 0.98; 95% confidence interval (CI) (0.78 to 1.22)], hypertensive disorders of pregnancy [RR: 1.08; 95% CI (0.82 to 1.43)], preterm birth [RR: 1.01; 95% CI (0.81 to 1.26)], or low birthweight [RR: 1.04; 95% CI (0.80 to 1.34)].

In this large cohort of women in Australian, initial associations between fertility problems and adverse pregnancy outcomes were attenuated after adjustment for key health and lifestyle factors. The absence of associations in fully adjusted models suggests that previously reported risks may reflect shared underlying maternal characteristics rather than infertility itself and highlights the importance of cautious interpretation of statistical significance in large observational studies.