A nationwide Danish registry revealed that no extra adverse effects arise from medical abortions on outcomes of the first subsequent pregnancies. The comparison included the outcomes of subsequent pregnancies of 2,710 women who underwent first-trimester medical abortions and 9,104 who had surgical abortions and the results showed similar rates of ectopic pregnancy, spontaneous abortion, preterm birth, and births with low birth weight.

The Danish registry contains information about all abortions, both medical and surgical, since 1970. Types and dosages of drugs used to perform medical abortions, mifepristone, misoprostol, combination of the two, or other prostaglandin analogs have also been recorded.

When they compared the outcomes of pregnancies after medical and surgical abortions, they found no difference in the adjusted relative risk for ectopic pregnancy (2.4% versus 2.3%); spontaneous abortion (12.2% versus 12.7%); preterm birth (5.4% versus 6.7%) and low birth weight (4.0% versus 5.1%).

Researchers reported that the rates of adverse outcomes in the study were consistent with previous studies and because the last study drew from the entire population of Denmark, the large sample provided sufficient power to detect a small effect, if one truly existed.