Women who conceive while using IUD more likely to have adverse perinatal outcomes

Women who conceive while using an intrauterine contraceptive device (IUD) have a greater risk of preterm delivery, low birth weight babies, bacterial infections, or losing a fetus, according to researchers at Ben-Gurion University of the Negev (BGU) and the Soroka University Medical Center. The research will be presented at the Society for Maternal-Fetal Medicine's 38th Annual Pregnancy Meeting in Dallas, Texas on January 29 to February 3.

"We believe this is the first report tracking children born to mothers using an IUD over a long timeframe," says Dr. Gali Pariente, a faculty member of the BGU Division of Obstetrics and Gynecology, BGU Faculty of Health Sciences and a clinical instructor at Soroka. "Working with a large sample over 23 years allowed us to investigate obstetric parameters that hadn't been examined previously in large groups."

IUDs are the most popular form of reversible contraception worldwide. Nearly as effective as sterilization, yet not as permanent, they are the preferred birth control method for 23 percent of female contraceptive users, according to a 2015 United Nations report on world contraceptive use.

An IUD is recognized as a foreign body by the uterus, which produces an inflammatory reaction that impairs sperm implantation. Adding copper or progesterone enhances this response and stimulates further barriers that inhibit sperm from binding with an egg. The risk of IUD failure is highest within the first year of insertion.

In this new study, researchers compared the outcomes of 221,800 deliveries from 1991 to 2014.

During that time, nearly one percent (203) of the women who delivered babies had an IUD which was removed early in the pregnancy, and six percent (149) retained their IUD throughout gestation.

Women who conceived with an IUD were more likely to have one or more adverse outcomes including:

• Preterm delivery - 14.3 percent who removed their IUD and 14.1 percent who retained their IUD had preterm deliveries vs. 6.8 percent without an IUD
• Bacterial infection (chorioamnionitis) - Nearly five percent who removed their IUD and 2.7 percent who retained their IUD developed a bacterial infection vs. 0.6 percent without an IUD
• Low birth weight - 11.3 percent who removed their IUD and 12.1 percent who retained their IUD delivered babies under five pounds vs. 6.6 percent without an IUD
• Perinatal mortality - Two percent who removed their IUD and 1.3 percent who retained their IUD lost the fetus vs. 0.5 percent without an IUD

The study, Perinatal Outcomes of Pregnancies in Women Who Conceived While Using an IUD, will be presented at the Society for Maternal-Fetal Medicine's annual conference in Dallas, Texas, January 29 to February 3 by Dr. Gali Pariente, Dr. Tamar Wainstock of BGU's School of Public Health, and Prof. Eyal Sheiner, M.D., Ph.D., vice dean for student affairs of the BGU Faculty of Health Sciences, member of the Division of Obstetrics and Gynecology, and head of the obstetrics unit at Soroka.

"Because of the elevated risks of severe, adverse short-term perinatal complications, we recommend careful monitoring of any women who conceive while using an IUD," says Dr. Pariente.