Spontaneous abortion, also known as miscarriage, refers to a pregnancy that ends spontaneously before the fetus has reached a viable gestational age. The management of different types of spontaneous abortion will be discussed here. Other aspects of spontaneous abortion, including the clinical manifestations and diagnosis of the different types of abortion, are reviewed separately. (See "Spontaneous abortion: Risk factors, etiology, clinical manifestations, and diagnostic evaluation".)
Women with threatened abortion have traditionally been managed expectantly until their symptoms resolve, a definitive diagnosis of nonviable pregnancy can be made, or there is progression to an inevitable, incomplete, or complete abortion.
The use of progestins to reduce the risk of miscarriage among women with threatened abortion is controversial. A meta-analysis that included four randomized trials with a total of 421 women found that the rate of spontaneous abortion was statistically significantly lower with progestin treatment compared with placebo or no treatment (14 versus 26 percent; relative risk 0.53; 95% CI 0.35 to 0.79) . Progestins were administered either orally or vaginally, and subgroup analysis found a significant decrease in the rate of abortion only for oral progestins; the analysis of vaginal progestins lacked sufficient statistical power to detect a difference. There was no significant increase in congenital anomalies or pregnancy-induced hypertension in the progestin group. However, the meta-analysis was limited by the small number of participants and events and poor methodological quality of studies. Many miscarriages are caused by genetic abnormalities in the conceptus. It is unlikely that progestins could prevent a miscarriage of this etiology. The data are insufficient to make a recommendation for or against progestins for women with threatened abortion.
Bed rest is commonly recommended, but randomized trials have not found that bed rest at home or in the hospital is beneficial in preventing fetal loss in women with threatened spontaneous abortion . Abstinence from sexual intercourse is also typically advised, although there are no data to support this.
There are no high quality data that support use of human chorionic gonadotropin, uterine muscle relaxants (eg, tocolytics, beta-agonists), or vitamin supplementation for preventing pregnancy loss in women with threatened abortion [3-5].