Currently, in the US, about one third of deliveries are by cesarean section.
The percentage of deliveries occurring by cesarean section has been increasing
steadily over the past few decades. The percentage of people affected by
infertility has also been increasing. Is it possible that having a C section
could make it more difficult to become pregnant again? Stay tuned.
A large study in the past of nearly 600 000 women reported that women who had cesarean delivery were
9% less likely to have a subsequent pregnancy and 11% less likely to have a subsequent live birth.
That study left some unanswered questions. For example, were the women who delivered by cesarean
less likely to want additional children or more likely to decide to delay subsequent
childbearing? Or were they less likely to be able to conceive as a result of having a C section?
The First Baby Study followed women after delivery for 3 years. The primary goals
of this study were to compare women who had vaginal deliveries or C sections and
determine how many were able to conceive after unprotected intercourse and how many were able
to deliver. They also looked at other factors such as whether miscarriage was more common.
This was a fairly large study. 2423 women completed the 36-month follow-up and 2046 reported
having unprotected intercourse during that time. 712 of them, or just under one third, were
delivered by cesarean. During the three years of follow up 77% of those who had a vaginal delivery
became pregnant again but only 69% of those who had a c section did - a difference of 8%.
When looking specifically at those women who were trying to conceive, 6% more women conceived after
a vaginal delivery compared to a C section. There was no difference in the rate of miscarriage.
Ultimately, the live birth rate was 50% after vaginal delivery and 43% after C section.
Researchers also looked at how quickly these women were able to get pregnant.
Starting at the 6th month of unprotected intercourse and every 6 month period
afterward, less pregnancies were conceived in the C-section group
This study adequately answers the questions we had before. We have confirmed that less women
are able to conceive and deliver a baby after having a C section. This difference isn't due
to them not wanting to have another pregnancy. Women who were actively trying to have another
baby were simply unable to get pregnant as often as those who had a vaginal delivery.
The next question is why? It wasn’t because they were having intercourse less often. It
wasn’t because of some identifiable factor in the women who had C sections such as
a difference in their weight or having problems getting pregnant the first time.
One possibility is a problem with the uterus itself. Recently, we have learned that some
women develop a defect at the site of the cesarean incision which is referred to as an isthmocele or
niche. Using ultrasound, about 60% of women with a c section can be found to have one of these
uterine defects. Some studies have suggested that this may increase risk of subsequent infertility.
It is also possible that cesarean section makes it more likely that the fallopian
tubes will become blocked. Studies have shown this occurs in about 15% of women
after a cesarean section but whether this is more than with a vaginal delivery is unclear
Another possibility is that scar tissue may form in the abdomen which makes it more difficult for
the egg to get picked up at the fallopian tube at ovulation. Finally, it has been reported that
the implantation rate and pregnancy rate after in vitro fertilization are significantly lower
among women with prior cesarean delivery than those with prior vaginal delivery.
Our Infertility TV Bottom line is this. It is more difficult to conceive again
after having a cesarean section though the reasons are unclear.
As the percentage of deliveries from cesarean section continue to increase
we would expect that the percentage of people with fertility problems will also increase.