How Long Do I Have to Wait to TTC After a C-Section?

Hi Emily, I have a four-month-old son who unfortunately had to be born via an emergency C-section. My husband and I were planning on trying to conceive a second child after our son turns 1. My OB recommended that I wait until 18 months postpartum to reduce the risk of a uterine rupture (even with a scheduled C-section for the next pregnancy). I have found data that there is a reduction in uterine ruptures and other complications if you wait 18 months or 6 months, but is the difference between waiting 12 and 18 months that significant? I am 34 and will be 35 by the time we try to conceive next, so I am also racing the clock. Thanks!
—New mom with distrusted timeline

I asked my friend and collaborator, Dr. Nathan Fox, MFM, to help me on this one — so the answer below reflects his thoughts too.—Emily

The advice you are getting (or the way you are reading it) is conflating two different things.

First, there is some general advice on waiting at least six months after birth (by any method) to conceive. The evidence base for this recommendation is fairly weak; there are some links with preterm birth, but this might reflect the fact that women who have short intervals between conception tend to be at higher risk for preterm birth for other reasons (age, for example).

Second, there is a recommendation that time from delivery to delivery should be at least 18 months if you’ve had a C-section. There isn’t much data on this, but there is some biological plausibility around scar healing time. This is most salient if you are planning a vaginal birth. The risk of uterine rupture is much smaller if you are planning another C-section, as it would only be a risk if you went into labor before the schedule.

In your particular case: waiting 12 months to try to conceive would give you a minimum of 21 months between births, which puts you outside of these risk windows. So feel free!