Track your baby's development, week by week

Your pregnancy: 6 weeks


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See what's going on in your uterus this week.


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Spotting (spots of blood on your underpants or toilet tissue after urinating) or bleeding is relatively common in early pregnancy, affecting up to a quarter of pregnant women. It may occur in a normal pregnancy, but sometimes it can be the first sign of miscarriage or an ectopic pregnancy. If you have any spotting or bleeding, call your provider.

The chewable alternative "My prenatal vitamins made me sick, so my doctor gave me a prescription for fruit-flavored chewable prenatal vitamins and suggested I take them with meals. That really helped." — Janice

Surprising Facts: Could it be twins?

Sure, twins run in families and you're more likely to be carrying multiples if you've undergone fertility treatments, but any woman can become pregnant with more than one baby. Could you be one of them?

Your odds of carrying twins

  • Overall, about one in 31 births (greater than 3 percent) are twin births. But your chances of having twins are much less — 1 in 89 — if you conceive without medical assistance. The overall odds of bearing triplets or higher-order multiples is about 1 in 565.
  • Identical twins usually happen by chance. Your likelihood of having identical, or monozygotic, twins (when one fertilized egg divides in half) is about 1 in 250.
  • A number of factors affect your odds of having fraternal twins or higher-order multiples. Fertility treatments dramatically increase your odds. On average, 20 to 25 percent of women who take fertility drugs or undergo in vitro fertilization or other assisted reproductive techniques end up carrying more than one baby.

Other factors that influence the likelihood of having fraternal twins

  • Once you have a set of fraternal twins, you're twice as likely to have another set in a future pregnancy.
  • Fraternal twins run in families, so if you're a twin or related to twins, you're more likely to have a set yourself. Your partner's family history doesn't appear to affect your odds of having twins.
  • The older you are, the greater your chances of having naturally occurring fraternal twins or higher-order multiples. Hormonal changes in older women are a likely cause.
  • Fraternal twins are more common than average in African Americans and less common in Hispanics and Asians.
  • The more pregnancies you've had, the greater your chances of having twins.
  • Twins are more common in large and tall women than in small women.

When you'll find out whether you're carrying twins

These days, women typically discover they're having more than one baby during an ultrasound, often in the first trimester. If you opt for first-trimester genetic screening, you'll have an ultrasound between 11 and 13 weeks. If you're pregnant as a result of a fertility treatment, you'll probably have an earlier ultrasound, usually within the first eight weeks to count the number of embryos that have implanted. Your practitioner also will recommend an ultrasound if your uterus is larger than would be expected given the number of weeks since your last period. Ultrasound is almost foolproof at revealing multiple pregnancies, particularly after six to eight weeks. However, the more babies you're carrying, the easier it is for one to get overlooked.

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Your Pregnancy, Week by Week
Your Pregnancy, Week by Week
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