Most women hope that they can deliver their baby vaginally, especially if it's their first. Having a baby is a unique experience, so it’s natural to want that connection with your offspring as opposed to the impersonal cesarean delivery. Unfortunately, vaginal deliveries are not always possible. My Aunt was telling me the story of her birth this weekend and mentioned something that caught my attention. In the delivery room as her contractions were just starting, a nurse came in and explained that she had to determine the size of the baby based on the stomach. She held by Aunt’s belly from different angles and claimed that nurses try to compare the size to a bag of sugar. Though the method seems outdated, it’s the best way to make a real call about the actual size of the baby prior to delivery.

Ultrasounds obviously work too, but when a nurse feels your belly in the delivery room she can get a good idea about how big the baby is compared to your frame. For example, a 200lb woman would have little trouble delivering a big 10lb baby, but a 100lb woman with a small frame might not be able to do so safely. When the nurse makes this final check, she is essentially visualizing the baby coming out of you and making sure the scenario seems realistic. If she determines the delivery would be too risky considering your size and your baby’s size, she will recommend a cesarean. No matter how badly you want to delivery vaginally, you’ll need to listen to the nurses and doctors if they make that call, because a vaginal delivery for a baby that is too large is dangerous for you and your infant.

There is no short answer to the question about how big is too big for vaginal delivery. Larger women can delivery larger babies. In my Aunt’s case, the nurse determined that her baby was much too large to delivery vaginally. Luckily, she was barely upset because she wasn’t looking forward to the pain anyway. You should accept the fact that your birth might not go as planned in advance so that you’re not heartbroken about anything on the day of delivery. No matter what happens, the staff of doctors and nurses will do their best to keep you and your baby healthy, which is the most important thing in the end anyway.

Source: Victoria Coleman et al: Rising Cesarean Delivery Rates. Obstetrical and Gynecological Survey Volume 64 Issue 2 pp. 115-119 February 2009