Enlarged Placenta: What Placentomegaly Means During Pregnancy

If your practitioner told you that you have an enlarged placenta, you might have what those in the medical profession like to call placentomegaly: a placenta that's grown disproportionately bigger than normal. That means the placenta is either thicker than it should be or weighs more than your doctor thinks it should (or both).

The placenta is the pancake-shaped organ in the uterus that serves as the baby's lifeline for nutrition, oxygen, and waste removal. It's usually one-sixth of the baby's weight and has a thickness that corresponds roughly to the baby's gestational age. For example, a fetus that's 20 weeks along would be nurtured by a placenta about 20 millimeters thick. At 24 weeks, the placenta is around 24 millimeters thick, and so on.

Key Takeaways:

• An enlarged placenta isn’t usually a reason to panic. The word is big (placentomegaly), but most of the time it doesn’t cause problems.
• Some conditions play a role. A larger placenta may be linked to hypertension, anemia, or diabetes — but your doctor will monitor these and the health of your baby.
• Your baby’s growth matters most. Even if your placenta measures big, steady fetal development is the important goal, so keep up your regular appointments to be sure everything’s right on track.

The sizes of placentas, however, vary widely from pregnant woman to pregnant woman. A better-nourished mom-to-be tends to produce a bigger, more productive placenta (but still within normal range) than that of an undernourished mom-to-be.

Although an enlarged placenta is not tremendously common, it's also not very rare. A few factors that can result in an enlarged placenta include smoking, certain infections in the uterus, and some maternal medical conditions, such as anemia, hypertension, or diabetes.

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The good news is that often an enlarged placenta means nothing more than, well, a larger-than-expected placenta. And unless your practitioner is concerned about it, there's little reason to worry.

The best gauge of a baby's health is development at a steady pace, and your doctor will certainly keep close tabs on that.

Good luck! Track your pregnancy weight with the My Journal tool in our free app