The number of twins born in the United States has greatly increased due to the increased availability and use of assisted reproductive technology such as in vitro fertilization. Twins occur in one in 41 pregnancies as of 2011, according to the American Congress of Obstetricians and Gynecologists. Twin pregnancies add special risks for both mother and baby. Getting the nutrients that all three of you need is essential when you're carrying twins. A woman having twins should not double up on her prenatal vitamins, however, unless instructed to do so by her physician. Extra supplementation of certain vitamins may be necessary.
Prenatal Vitamins
One standard prenatal vitamin will meet your needs if you're having twins, BabyCenter states. One reason not to double up on prenatal vitamins is to avoid getting too much vitamin A. In large doses, vitamin A can cause birth defects in infants as well as liver toxicity in mothers. If you need specific additional nutrients, it's best to take them in individual supplements rather than doubling up on prenatal vitamins.
Folate
Folate, one of the B-complex vitamins, helps prevent neural tube defects such as spina bifida and anencephaly. Folate deficiency may occur more frequently in a twin pregnancy than singleton pregnancy, author Michael de Swiet reports in "Medical Disorders in Obstetric Practice." Folate deficiency may affect as many as one in 11 twin pregnancies compared to one in 80 singleton pregnancies, according to de Swiet. Prenatal vitamins normally include between 400 and 800mcg of folate, but your doctor may prescribe additional folate beyond the amount in your prenatal vitamin.
Iron
Because pregnancy increases your blood volume, you need additional iron to supply your increased volume of red blood cells with enough oxygen. Women carrying twins may be more prone to developing iron deficiency in pregnancy. While prenatal vitamins do contain iron, your doctor may prescribe additional iron to meet your increased needs. Iron supplements can cause constipation, a common complaint in multiple pregnancy; ask your doctor to prescribe a stool softener if constipation becomes a problem.
Calcium
Growing fetuses need calcium to grow skeletal tissue. Adequate calcium intake may also reduce the risk of pre-eclampsia, a serious pregnancy complication characterized by fluid retention and often accompanied by high blood pressure. The risk of developing pre-eclampsia increases when you're having twins, registered dietitian Barbara Luke warns. Do not take iron and calcium supplements at the same time, since calcium may interfere with iron absorption.
Additional Supplements
Your doctor may suggest taking extra magnesium and zinc if you're having twins. Magnesium may help reduce the risk of uterine contractions and preterm delivery, a common occurrence in multiple pregnancy. Magnesium along with zinc may aid with the development of a healthy nervous system and may also help decrease common pregnancy symptoms that are magnified in twin pregnancy such as leg cramps, difficulty sleeping and heartburn, according to Dr. Luke. Do not take additional supplements without your doctor's approval.
References
- Ask the Dietitian; Pregnancy and Morning Sickness; Joanne Larsen, R.D., M.S.
- American Congress of Obstetricians and Gynecologists; Having Twins; December 2004
- Dr. Barbara Luke; Vitamin and Mineral Supplements: Your Nutrition Insurance Policy; Barbara Luke, R. D., ScD
- BabyCenter; Vitamin A in your pregnancy diet; August 2009
- "Medical Disorders in Obstetric Practice"; M. De Swiet; July 2002
