Fetal Complications in Multiple Pregnancies

Infants born from multiple pregnancies are at risk for various complications. Multiple pregnancies often require aggressive neonatal intensive care, which is costly and stressful for the family and the infants.

Low birth weight—Birth weight below 2500 gm is considered low, and birth weight below 1500 gm is considered very low. This condition results from having less room to grow in utero. Two-thirds of infants born from a multiple pregnancy are low birth weight and are at risk for significant short-term and long-term health problems as a result.

Birth defects—Monozygotic twins (develop from one egg that divides into two) are twice as likely as dizygotic twins (develop from two fertilized eggs) to be born with congenital malformations.

Infant mortality—Infants born from a multiple pregnancy are at a greater risk for infant mortality and mental and physical problems that can result from premature delivery. Most infant mortalities in preterm multiple deliveries occur in gestations less than 32 weeks and birth weights below 1500 gm. Respiratory distress syndrome (RSD) accounts for 50 percent of neonatal deaths resulting from premature birth.

Cerebral palsy—Infants born from a multiple pregnancy have a higher risk for cerebral palsy and other types of permanent neurological damage.

Multifetal Pregnancy Reduction (MFPR)

Some couples choose to reduce the number of fetuses to lessen the risk for maternal and fetal complications. The decision to undergo multifetal reduction is difficult, and the experience can be traumatic. The procedure is usually performed when there are 4 or more fetuses. About 4-5 percent of women who undergo multifetal reduction miscarry the entire pregnancy as a result of the procedure.

Multifetal reduction is an outpatient procedure that is most successful when performed between 10 and 12 weeks of gestation. It involves using ultrasound to guide the insertion of a needle through the abdomen to inject potassium chloride into one or more of the fetuses.

Multifetal reduction is sometimes performed earlier in the pregnancy (between 6 and 8 weeks) using a transvaginal approach and embryo aspiration. This procedure is performed less often because it requires general anesthesia and carries a risk for infection. There is a chance for spontaneous fetal reduction at this stage, and it is too early in the pregnancy to perform fetal screening for defects.

Multiple Pregnancy Management

Patient education and trained health care providers can significantly reduce medical complications and mortality associated with multiple births. Hospitals that deal with high-risk pregnancies and deliveries sponsor support groups for the parents of multiple births.

Patients should be monitored carefully during fertility drug treatment to prevent a multiple pregnancy. During in vitro fertilization (IVF), the number of embryos transferred should be limited and should be based on the mother's age and the quality of the embryos.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 31 Oct 2000

Last Modified: 01 Oct 2015