Length of a 'normal' pregnancy can vary

Drs. Oz and Roizen explain woman's odds at delivering late and the future of printing technology.
BY MICHAEL ROIZEN, M.D., AND MEHMET OZ, M.D. Published: September 9, 2013
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Q: I'm pregnant with my second child. In my first pregnancy, I had labor induced when I was 14 days past my due date. Am I going to have to go through that again?

Mary P. Greenville, S.C.

A: Maybe (see below). But first, some great pregnancy facts! The longest pregnancy was reported by a doctor at Los Angeles Methodist Hospital in 1945: 25-year-old Beulah Hunter supposedly gave birth to a 6 pound, 15 ounce baby girl after carrying her for 375 days — 95 days longer than the 280 that women are told is “normal.” While it seems unlikely the claim is accurate, it does make you wonder, because finally researchers have figured out the length of a normal pregnancy can vary by as much as 37 days!

And how did they determine this? Well, scientists compared urinalysis results from a large group of pregnant women to determine exactly when each woman ovulated and when a fertilized embryo implanted in her womb, and then tracked the women throughout their pregnancy. They discovered that 268 days (or 38 weeks and 2 days) is average for a full-term birth. And it's not abnormal for it to take much longer. It's interesting to note that only 4 percent of women deliver at 280 days, and 30 percent do not deliver within 10 days of their estimated due date.

Whether the length of your pregnancy is normal but simply longer-running than most is something only you and your doctor can determine. But one thing the researchers found was that while “full term” varies from woman to woman, for any one mom, the length of her pregnancy is pretty consistent from child to child.

For more helpful info, take a look at our book “YOU: Having a Baby.” And work with your doctor to monitor the development of the fetus throughout your pregnancy. When it comes to the last stages, do what you must to protect your health and the health of your child. Congratulations!

Q: I'm fascinated by the new 3-D printers; I can't wait to manufacture things at home for myself and the kids. But I hear they may be a health hazard. What's that about?

John P., Minneapolis

A: We also love technology that makes life simpler and easier. Who doesn't? But you're right, at-home 3-D printers come with some pretty serious risks. Remember “Na-Nu, Na-Nu,” the friendly Orkan greeting that extraterrestrial visitor Mork (Robin Williams) used when meeting Earthlings? Well 3-D printers come with a similar, “Nano Nano” greeting, but the meaning isn't so friendly.