Almost 40% of Assisted Reproductive Infants Are Multiple Births Interview with:
Saswati Sunderam, PhD

Division of Reproductive Health
National Center for Chronic Disease Prevention and Health Promotion
CDC. What is the background for this study?

Response: Assisted Reproductive Technology Surveillance – United States, 2014, the surveillance summary published this week in CDC’s Morbidity and Mortality Weekly Report (MMWR), presents state-specific data on assisted reproductive technology (ART) use and outcomes.

The report compares ART infant outcome data with outcomes for all infants born in the U.S. in 2014, and provides data on the contributions of  Assisted Reproductive Technology to total infants born, multiple birth infants, low birth weight infants, and preterm infants for each U.S. state, the District of Columbia, and Puerto Rico. What are the main findings?

Response: The report provides a number of important data points, but some of the key findings include:
• In 2014, approximately 1.6 percent of all infants born in the United States were conceived with Assisted Reproductive Technology.
• The national percentage of elective single embryo transfer increased from 7.4 percent in 2009 to 28.5 percent in 2014 among women under 35 years of age. From 2013 to 2014, it increased about 33 percent among women in that age group.
• Approximately, 39.4 percent of ART infants were born in multiple births compared with 3.5 percent among infants born in the general population. Approximately, 95% of ART-conceived multiple birth infants were twin infants.
• A greater proportion of Assisted Reproductive Technology infants were low birth weight (28 percent), and preterm (33 percent), compared with infants in the birth population overall (8 percent and 11.3 percent, respectively). What should readers take away from your report?

Response: Single embryo transfer procedures can reduce multiple births from Assisted Reproductive Technology treatments. Increasing the use of elective single embryo transfer (eSET) procedures when clinically appropriate could help reduce multiple births and related adverse health consequences. Despite the increases in the use of eSET procedures in recent years, greater than 95% of ART-conceived multiple birth infants were twin infants in 2014. Improved provider practices and patient education and counseling on the maternal and infant health risks of having twins and on the effectiveness of eSET procedures are needed.

Although ART contributes to high percentages of multiple births, other factors not investigated in this report (e.g., delayed childbearing and use of non-ART fertility treatments) also contribute to multiple births and warrant further study. Is there anything else you would like to add?

Response: Since the birth of the first child conceived via ART in 1981, the use of advanced technologies to overcome infertility has increased, as has the number of fertility clinics providing ART services and procedures in the United States. Although Assisted Reproductive Technology has helped millions of infertile couples achieve pregnancy, it is associated with potential health risks to both mother and infant. Transferring multiple embryos – which, as this report confirms, occurs in the majority of ART procedures – often results in multiple-gestation pregnancies and multiple births. Risks to the mother from multiple births include higher rates of caesarean deliveries, maternal hemorrhage, pregnancy-related hypertension, and gestational diabetes, with risks to the infant including prematurity, low birthweight, infant death, and elevated risk for birth defects and developmental disability. It is encouraging to see an increase in the number of elective single-embryo transfers (eSET) among women under 35 years old, but it’s clear that there’s more work to do to encourage eSET among women with a good chance of success with Assisted Reproductive Technology.

These findings will allow state health departments to monitor the extent of ART-related adverse perinatal outcomes among singletons, twins, and triplets and higher-order infants in their reporting areas. CDC is working to improve patient education and counseling on the comparative benefits of single versus multiple embryo transfers. For more information, see here. Thank you for your contribution to the community.


Sunderam S, Kissin DM, Crawford SB, et al. Assisted Reproductive Technology Surveillance — United States, 2014. MMWR Surveill Summ 2017;66(No. SS-6):1–24. DOI:

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.

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