Multiple Births

The allure of twins or multiples! What’s the reality?

The advent of Assisted Reproductive Technologies (ART) has revolutionized the treatment of infertility patients. Many couples who would not have been able to a have biological children a generation ago are now able.happy-family-in-the-kitchen However, like many revolutionary changes in society, the science of assisting human fertilization is evolving and still has some negative outcomes.

The media’s portrayal of excitement and joy when multiple births arrive is misleading: there can be real, life-long physical and emotional health consequences for these tiny babies. Parents must grapple with the financial and emotional toll of residual health challenges long after the glare of public attention fades. This article reviews the risks of multiple pregnancy outcomes for parents and their children.

The magnitude of the problem of multiple births

The multiple birth rate statistics for in-vitro fertilization (IVF) are by law reported to SART, an organization that compiles these statistics and makes them available to consumers on their website at: In 2000, the national pregnancy rate per ART cycle with fresh, non-donor eggs was 30.7%. More than 1/3 of these pregnancies were multiple births. When fresh donor eggs were used, the multiple pregnancy rate exceeded 42%. Women who use donor eggs are an older population, and women over 35 endure elevated complication rates during pregnancy. Multiple pregnancy magnifies any age-related risks.

The occurrence of twin births in the US has increased 76% since 19801, and the occurrence of triplets or more has increased 404%. Furthermore, the increased number of women using ART is directly related to the increased number of women delivering more than one baby. Despite continuing debate, research, and numerous publications about the consequences associated with multiple births, the US has a high-order multiple pregnancy rate twice the rate of our European counterparts.

Maternal complications during multiple birth pregnancies

The stress on the mother’s bodily functions is elevated during a multiple pregnancy. The risks that increase include: hypertensive disorders, clotting disorders, a urinary tract infection, anemia, and increased risk of vaginal-uterine bleeding incidents that can compromise fetal health.

Months of bed rest are often required to lengthen gestation and decrease premature delivery. This lengthy confinement may cause unanticipated emotional and financial hardships, especially if there are other children at home. The discomfort of injectable medical interventions for gestational diabetes, excessive swelling and premature contractions strain the mother’s emotional and physical well-being, as family dynamics shift to help keep Mom and baby safe. The risk of maternal death, though low, is 3-fold greater with a multiple pregnancy than with a singleton pregnancy.

Consequences to the infants who are part of a multiple pregnancy

Approximately 50% of all twin pregnancies and 90% of all higher-order pregnancies will result in infant births that are pre-term and have low birth weight (less than 5 lbs 8 oz). Premature births are the second leading cause of infant death in the US. (Birth defects are the leading cause of infant death). The use of ART has been identified as a major contributor to the increase in pre-term births. The chart below reports the outcome from the Swedish National Vital Statistic Report of 2002.

% babies born before 37 weeks 10.4% 57.4% 92.4% 97.8%
% babies born before 32 weeks 1.6% 11.8% 36.7% 64.5%
% babies born with low birth weight 6% 54.9% 94% 98%
% babies born with very low birth weight 1.1% 10.2% 34.8% 68.4%
Mean birth weight 7.3 lbs 5.2 lbs 3.7 lbs 2.8 lbs

Infants born too soon have many obstacles to overcome. The earlier the infant is born, the less developed its organs will be, leading to a greater risk of problems. Some common problems include:

    • Breathing

Breathing requires mature lungs which must have a substance called surfactant to function properly. Respiratory distress syndrome (RDS) occurs when the surfactant is lacking. Medication providing the missing surfactant can be given, and additional oxygen delivered via nasal canula or a respirator will assist fragile lungs in the early weeks. Very premature babies may develop permanent lung damage.

    • Bleeding in the brain

For low birth weight infants, especially if the birth weight is less than 3 lbs 5 oz., excess blood vessel leakage can occur and cause brain damage. Medications and sometimes surgery are used to treat this complication.

    • Immature digestive systems

Premature infants struggle to absorb nutrition. Sometimes the intestinal tissue is so immature that portions of it die. This leads to infection and nutritional deficits. Treatment includes antibiotics and surgery.

    • Heart problems

An immature heart has difficulty assuming the challenge of the infant’s circulatory needs. One major problem involves the immediate and crucial closing of an artery called the ductus arteriosis. After birth, in order for the baby’s blood to circulate within its own body (i.e., without the placenta’s help), the ductus arteriosis must close. Premature babies often need help to get this artery to close. Medication and sometimes surgery may be necessary.

    • Eye risks

The retinas in the premature infant’s eyes may have an overgrowth of blood vessels (rentinopathy), which can cause visual loss. For some infants this resolves itself, while others may need laser or freezing therapy to preserve vision.

    • Lack of body fat

The tiny, frail premature infant does not have enough body fat to preserve its body temperature. An incubator will help. Unstable body temperature increases the severity of any other complications.

    • Cerebral Palsy

An estimated 5-8% of infants weighing less than 3 lbs. 5 oz. at birth will develop cerebral palsy. This is 25 times the risk of a full-term infant weighing 5 lbs. 8 oz. or more. Bleeding in the brain (see above) may cause pressure and damage on the part of the brain that controls motor function, thus increasing the risk of cerebral palsy.

Care of the premature infant requires a coordinated team effort of physicians, nurses and parents. Special units in hospitals called neonatal intensive care units (NICU) exist to deliver life saving therapies for premature infants. NICU care offers tremendous hope for premature infants. However, despite the best efforts of medicine, ten percent of premature infants will die. Lifelong neurological and physical handicaps will affect another 25%.

Increasing the chance that you will have a healthy singleton live birth.

  1. Listen carefully to your doctor’s counseling. The doctor will share the risks of ART and what the team will do to reduce these risks. Ask questions, and share your expectations for pregnancy outcomes. Ponder carefully the number of embryos that you will allow to be transferred. Choose an ART center with a low multiple birth rate.
  2. Take your prenatal vitamins. Start 2-3 months before ART for optimal nutritional protection.
  3. Question every prescription or over-the-counter medication that you take. Is it safe for pregnant women? Let prescribing doctors and dentists know you are attempting pregnancy.
  4. Avoid all herbs.
  5. Work closely with other physicians to control any chronic health problems such as diabetes, hypertension, rheumatoid arthritis, or depression.
  6. Utilize stress reduction techniques. These include regular exercise, music, acupuncture, and massage.
  7. Stop smoking and limit alcohol intake.
  8. Discuss your weight with your physician. If necessary, follow any suggestions for weight loss prior to conception.

The Good News

It is possible to limit a couple’s risk of a multiple pregnancy. Single embryo transfers are being offered to couples at high risk for multiples. Many centers limit the number of embryos transferred to 2 embryos in women under 35, and 3 embryos in women over age 35. You can help. Your expectations and desires have a strong influence on your doctor. Take the time to understand what your risk is of twins and triplets or more. Talk to your doctor about the best way to limit this risk while still giving you the best chance of becoming pregnant. It’s your future and your children’s future; you should be an active participant in the decisions!


  1. 1Three Decades of Twin Births in the United States, 1980–2009
  2. Moos, MK. (2004). Understanding prematurity: sorting fact from fiction. AWHONN lifelines, 8(1), 32-37.
  3. Bergh et al. (1999). Deliveries and children born after in-vitro fertilisation in Sweden, l982-95: a retrospective cohort study. Lancet, 354, 1579-85.
  4. Infertility therapy-associated multiple pregnancies (births): an ongoing epidemic. (2003) Proceedings of an expert meeting. Bertarelli Foundation New York April 12-13. Reproductive Healthcare Ltd, Vol 7-Suppl 2:Cambridge
  5. Ryan FL, Zhang SH, Dokras A, Syrop CH & Van Voorhis, BJ. (2004). The desire of infertile patients for multiple births. Fertil Steril, 81, 500-511.
  6. Escobar GJ, Littenberg B & Petitti DB. (1991) Outcome among surviving very low birthweight infants: a meta analysis. Arch Dis Child.66(2), 204-11.
  7. March of Dimes article on Multiples: Twins, Triplets and Beyond.
  8. March of Dimes Article on Low Birthweight.
  9. The Alfred I. Dupont Institute. Cerebral Palsy: a guide for care.