# Delivery mode and subsequent birth rate: A nationwide register‐based analysis in Finland

## TL;DR

This study found that women who had a cesarean section were less likely to have another child compared to those with a vaginal birth, suggesting other factors influence birth rates.

## Contribution

The study provides new evidence that factors beyond the type of delivery affect subsequent birth rates, using a large national dataset.

## Key findings

- Women who had an elective cesarean section had a lower subsequent birth rate compared to those with spontaneous vaginal delivery.
- Assisted vaginal delivery and unplanned cesarean section were associated with higher subsequent birth rates.
- The study suggests underlying factors, not just delivery mode, influence birth rates after the first child.

## Abstract

The study aimed to calculate the subsequent birth rate for different delivery modes, comparing them with spontaneous vaginal deliveries, using a comprehensive nationwide high‐quality registry.

Data from the National Medical Birth Register (MBR) were used to evaluate the birth rate after different delivery modes. All first deliveries for a mother during the years 2004 to 2016 were included. For these women, all second pregnancies from the MBR during the years 2004 to 2018 were retrieved and combined with the data of the first deliveries. A Cox regression model was used to evaluate the risk for the second pregnancy after giving birth the first time. The results were interpreted with adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs).

A total of 375 619 women with a first and second pregnancy leading to birth were included in this study. Of these, a total of 50 579 women underwent assisted vaginal delivery, 50 429 had an unplanned cesarean section (CS), 22 021 had elective CS, and 252 593 had spontaneous vaginal delivery as a mode of delivery in their first pregnancy. Women with assisted vaginal delivery (aHR, 1.23 [CI, 1.21–1.24]) and unplanned CS (aHR, 1.03 [CI, 1.02–1.05]) had higher birth rates after the first birth, and women with elective CS as a mode of delivery had lower birth rates (aHR, 0.86 [CI, 0.84–0.88]) when compared with women who had spontaneous vaginal delivery.

The findings of this study indicate that the CS operation itself is not the only cause of the observed lower birth rate; rather, there are underlying factors that have a greater impact on birth rates.

Cesarean section itself is not the only cause of the observed lower birth rate; there are underlying factors that have a greater affect on birth rates.