How Successful is TOLAC After Two C-Sections?

I ended up with an emergency C-section for my first. I then opted for a scheduled C-section for my second, on doctors’ advice. If I were to have a third child, I’ve read that the success rate of trial of labor after cesarean (TOLAC) after two C-sections is actually not much different than the success rate after one C-section. However, my doctor seemed very squirrelly about doing a TOLAC after two C-sections. What does the data actually say?
—Millennial Overthinker

There are at least two considerations on your plate here, medically. One is the probability of success — will the trial of labor lead to a vaginal birth? — and the second is uterine rupture — what is the size of that risk? Your question is really whether the success probability or the risk is affected by the fact of your two cesarean births.

This is a very difficult question to answer with data. The problem, from a data interpretation standpoint, is that there is limited random variation to use when we are studying methods of birth. This is especially true when we are talking about, say, two cesarean sections rather than one. Having had a second cesarean after a first one will, on average, reflect something about the patient. To the extent that this is correlated with other birth outcomes or risk factors, it’s hard to separate out the impact of the C-section.

Having said this: the data we do have does not strongly differentiate between one and two C-sections. The success rates are similar (in the range of 65% to 85%), and the risk of uterine rupture appears to be slightly higher (in one meta-analysis, it’s 1.5% versus 0.75%). This data isn’t perfect, since the definition of “rupture” varied across studies, and the increase is overall small.

There is no strong prohibition against a trial of labor in this case — generally, medical advice focuses on informing the patient and evaluating their preferences. One note: the largest risk to an additional C-section is the risk for future pregnancies. If you very much want a fourth child, that is going to argue for a trial of labor, since increases in the number of C-sections increases the risk of other placental complications.

This is the conversation I would bring to your doctor! Squirrelly or not…