Probability of second live birth after first natural and medically assisted reproduction-mediated live birth: A historical cohort study

Introduction: Evidence on the role of medically assisted reproduction (MAR) in achieving the desired number of children is very limited. The aim of the current investigation was to assess the probability and the mode of conception of a second live birth according to the mode of conception of the first one.

Material and methods: This historical cohort study was based on administrative data from regional healthcare databases. Women hospitalized for childbirth in Lombardy between January 1, 2007 and December 31, 2017 were identified. The probability of a second live birth up to 2021 was estimated using the Kaplan-Meier method. We calculated this probability according to the mode of conception of the first birth, and the analysis was also performed in strata of maternal age at first birth. Cox proportional hazards models were fitted to estimate the hazard ratio (HR) and 95% confidence interval (CI) of the association between mode of conception at first live birth and the probability of having a second live birth. Mothers were right-censored if they moved out of the region, died, or did not have a second live birth by the end of follow-up.

Results: We identified 431 333 women who had their first live birth after a natural conception and 16 837 who had their first live birth after MAR. The probability of having a second live birth was 58.6% and 32.1%, respectively in the two groups (HR = 0.68, 95% CI: 0.66-0.70). Considering solely women who naturally conceived their first live birth, the probability to have a second child with MAR was 1.1% and to have a second child naturally 59.3%. The corresponding values were 11.5% and 25.2% in the group of women with a first MAR-mediated live birth.

Conclusions: In our cohort, one woman out of 10 having a first MAR-mediated live birth underwent MAR programs again. Considering women who had a first natural live birth, this proportion was drastically reduced. In the field of MAR, more attention should be given to the capacity of a couple to achieve the number of desired children.