Risk factors for extrauterine pregnancy in women using an intrauterine device.

OBJECTIVE

To identify the risk factors for ectopic pregnancy (EP) in women using an intrauterine device (IUD).

DESIGN

Case-control study.

SETTING

Auvergne region (France).

PATIENT(S): Women using an IUD and suffering EP (243 cases) or having an intrauterine pregnancy (140 controls).

INTERVENTION(S): None.

MAIN OUTCOME MEASURE(S): Sociodemographic characteristics, smoking, medical history, and medicines taken before the pregnancy. Type of IUD, duration of use, position and visibility of the thread at diagnosis, and presence of abnormal clinical signs.

RESULT(S): Seven factors were associated with an increase in the risk of EP: histories of spontaneous abortion, IUD use, and tubal damage; progesterone IUD at the time of conception; insertion of an IUD during the month following a previous pregnancy; duration of use of the IUD in place at the time of conception; and pelvic pain resulting in medical consultation after the insertion of the IUD. Conversely, five factors were associated with a decrease in the risk of EP: history of treated low genital tract infection; history of contraception using the progestagen pill; use of paracetamol or aspirin before the pregnancy; and displacement of the IUD.

CONCLUSION(S): This study suggests that the IUD itself may have an etiological role in EP.