How do you get pregnant with twins or more?

by Julie Snyder

Twins or morePregnancy announcements and especially multiple births dominate celebrity news. That's not surprising.

When setting out on the parenting journey, most of us -- celebrities included -- envision welcoming one baby at a time. A growing number find themselves bringing home two or more at once.

Between 1980 and 2000, the number of twin births in the United States has risen by almost 75 percent. The number of higher-order multiples has gone up more than 400 percent. About three of every 100 babies are multiples.

Pregnancy multiplication -- twins and more

Your twin risk factors

Twins comprise the majority of multiple births -- about 95 percent. Are you curious about your own twin "risk factors?" You're more likely to have fraternal twins if:

• Twins run in your family
• You're over age 30
• You're tall -- in the top 25th percentile of height
• Your body mass index over 30
• You've recently quit using hormonal birth control
• Use assisted reproduction techniques

Different type of multiples

Identical (monozygotic) multiples: One egg splits early in pregnancy and develops into two or more fetuses. These babies will all be the same gender and look alike.

Identical twins sometimes share one placenta and might share an amniotic sac. Having identical twins is believed to be a random event, not linked to age, family history or other factors.

Fraternal (dizygotic) multiples: Each fetus forms from a separate egg and sperm. These babies can be the same or different genders and look no more like each other than normal siblings.

Higher-order multiples: Triplets, quadruplets and more are variation of identical and fraternal multiples. For example, triplet occur if one egg fertilized by one sperm splits into thirds or if two fetuses develop from two eggs and two sperm, then one splits into two. Similar scenarios occur in other forms of multiples.

Detecting multiples

If your mom had twins, she may not have known until the delivery room. Now ultrasounds show multiples as early as five or six weeks into the pregnancy. As many as 95 percent of multiples are discovered during the first trimester.

Your midwife or doctor might also suspect twins or more after hearing more than one heartbeat, if you're gaining a lot of weight, if your uterus is much larger than your gestation age suggests or if you have severe morning sickness compared to a previous pregnancy.

When you're pregnant with multiples

Your pregnancy is usually considered high-risk. You'll probably see your doctor more often than if you were carrying a single baby. You'll most likely get to see more "pictures" of your babies, too.

You may face an increased risk of complications that include preterm labor, gestational diabetes, pre-eclampsia, low birth weight and anemia. Your baby is more likely to arrive via cesarean.

Are you or were you pregnant with twins or more? How early in pregnancy did you discover you'd be bringing home more than one baby?

Photo courtesy of iStockphoto.