Christa B. spent every night of the last six weeks of her pregnancy sleeping in a chair. “I had such bad heartburn, I couldn’t lie down at all,” says Christa, 37, who lives in Portsmouth, N.H. and has a 14-month-old daughter. Her symptoms began relatively mildly during her first trimester when formerly favorite foods such as pizza triggered a burning sensation in her chest. “Then it became progressively worse,” she recalls. “I got heartburn when I tried to lie down or even just bend down. It was horrible.”

She’s hardly alone. It’s estimated that 30% to 80% of all women experience heartburn at some point during pregnancy. Some, like Christa, start feeling the burn in their first trimester. More typically, heartburn flares up later, around the five-month mark, and gets worse as pregnancy progresses. The good news? After your baby arrives, pregnancy-related heartburn will be a faint memory.

Why Heartburn Happens

To understand why pregnancy brings on the burn, you’ll need a quick lesson in how heartburn happens at all: It’s caused by acid that flows back up from the stomach into the esophagus during digestion—an action called reflux. Your stomach lining is well equipped to withstand acid, but your esophagus is more delicate, which explains the burning sensation.

Normally, a valvelike muscle at the entrance to the stomach called the lower esophageal sphincter (LES) opens when you swallow food, then closes to keep stomach contents and digestive acids from escaping. But in pregnancy, two factors cause the LES to relax.

• Hormonal changes. When you get pregnant, levels of progesterone as well as other hormones increase dramatically. Progesterone’s job—among other things—is to loosen and soften ligaments and other tissues, preparing your body for birth. Unfortunately, this loosening also affects the LES. At the same time, pregnancy hormones slow the entire digestive process, leading to indigestion and other gastrointestinal problems that may exacerbate heartburn.
• Increasing size and weight. The bigger your uterus gets, the more it crowds other organs, including the stomach and intestines. That’s why bouts of heartburn tend to be more frequent later in pregnancy. Your baby’s increasing bulk presses on the stomach, forcing some of the stomach’s contents back up into the esophagus.

Read about how to treat pregnancy-related heartburn safely and effectively.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis or recommended treatments. For severe heartburn or heartburn that persists after trying over-the-counter treatment or lifestyle modifications, visit your doctor to determine the right treatment for you. See the Terms and Conditions for more information.