Women who have a Caesarean delivery for their first child go on to have fewer children than women who give birth in the traditional way. This is shown in a study from the Norwegian Institute of Public Health (NIPH) and University of Bergen.

Researchers at the NIPH’s Medical Birth Registry and the University of Bergen have collected data on all first-time births from 1967-1996 and subsequent births until 2003. This covers nearly 600 000 births, so the results are statistically significant.

– Our finding confirms that from other studies; that women who give birth to their first child by Caesarean section less frequently have child number two and three than women who give birth in the normal way. We have looked further to see which births the reduced fertility concerns, says researcher and head physician Dr Kari Klungsøyr from the Medical Birth Registry.

The study is published in the journal Obstetrics and Gynecology and is a joint effort between the Department of Public Health and Primary Health Care at the University of Bergen and the NIPH. The main author of the publication is Mette Tollånes from the University of Bergen.

12 percent lower
The results show that if the child was stillborn or died in the first year of life, the number of subsequent pregnancies was not reduced. If the child survived, however, there were more women who did not have more than this one child, compared with women who gave birth in the traditional way.

The figures are as follows for women who had their first child between 1982 to 1996, who were then monitored until 2003:

  * Probability of having child number two for women who had a Caesarean section: 12 percent lower than for women who gave birth vaginally.
  * For the sub-group who had a child who was stillborn or died in the first year: probability of having child number two was the same as for women who gave birth in the usual way.

Unknown causes

- How can we explain this finding?

- We do not think it has anything to do with the medical reason for the Caesarean section, or any physical consequences of the operation. We can ask ourselves if it is such that if the women have had the child they want, maybe some cannot bear the thought of pregnancy, birth and any new operational procedures, says Klungsøyr.

Reference
Tollånes MC, Melve KK, Irgens LM, Skjærven R. Reduced fertility after Caesarean delivery – a maternal choice –Obstet Gynecol 2007; 110: 1256-63.

Source: Norwegian Institute of Public Health, PO Box 4404 Nydalen, N-0403 Oslo