Twins and Multiples: Are You Having More than One?

Indicators of a Twin-Plus Pregnancy

The technology to discern whether a woman is carrying more than one fetus has improved so much that it's possible to detect additional embryos very early in a pregnancy. For those who have taken fertility medication or had procedures like in vitro fertilization (IVF), you've got a very good chance of having twins. You may be able to determine if you're carrying multiples by taking a blood test that measures the amount of pregnancy hormone in your system. If the quantity of the hormone is higher than what would typically be expected for a single pregnancy, your healthcare professional may opt to give you an ultrasound as soon as six weeks into the pregnancy. The ultrasound can determine whether there's more than one gestational sac in your uterus.

If you have a family history of multiple births or exhibit signs of a possible twin-plus pregnancy, you can request an ultrasound, though some insurers have restrictions on how many ultrasounds a patient may have. But if your doctor thinks you've got a multiple pregnancy on your hands, it's likely you'll be given the go-ahead to have an early ultrasound.

If you haven't taken fertility medication and haven't had any medical assistance to get pregnant, here are some signs that may indicate a multiple pregnancy:

• Unusual weight gain
• Large uterus
• Extreme fatigue
• High pregnancy hormone levels in blood
• Pressure in pubic area
• Severe nausea

"A twin pregnancy is likely to show additional weight as early as the first trimester due to increased blood volume and uterine size," according to Twins! Pregnancy, Birth and the First Year of Life, by Dr. Connie Agnew, MD, Dr. Alan Klein, MD, and Jill Alison Ganon. "But sometimes a woman and her practitioner do not discover the twin pregnancy until the second trimester, when considerable weight gain raises their suspicions."

According to Twins!, the average weight gain ranges for single pregnancies are: five to seven pounds in the first trimester, 10 to 12 pounds in the second trimester, and 10 to 15 pounds in the third trimester. However the typical ranges of twin pregnancy weight gain are: five to 10 pounds in the first trimester, 10 to 15 pounds in the second trimester, and 15 to 20 pounds in the third trimester.

And if you're gaining weight rapidly, don't be surprised when, after they learn your due date, strangers tell you that they're sure you're going to have twins. "By the sixth month, a mother of twins may be so large that she tires of friends and strangers asking if delivery is imminent," quips Elizabeth Noble in Having Twins And More.

Uterine size can also be an indicator. "A uterus that seems exceedingly large based on the date of the last menstrual period is a very strong indicator of a multiple pregnancy," Agnew and her colleagues write. They also report that increased fatigue—beyond typical first trimester tiredness, water retention and pressure in the pubic area may signify a twins (or more) pregnancy.

Paula Spencer, author of Parenting Guide to Pregnancy and Childbirth, agrees. "[A multiple pregnancy] may be discovered in the first trimester if your uterus is growing faster than normal, if more than one heartbeat is detected, or if you're particularly nauseous," Spencer writes, adding that many sets of twins are discovered in mid-pregnancy by routine ultrasounds. The National Organization of Mothers of Twins Clubs' website says that according to its 1991 membership figures, 78 percent of the women learned they were carrying twins by their second trimester, while a total of 83 percent knew before delivery.

Of course the only way to be sure is to have an ultrasound. "In an initial evaluation during the first trimester, the ultrasound can be invaluable in documenting the number of gestational sacs present, and then looking for the number and size of the embryos that inhabit them," according to Twins!