Multiple Unintended Pregnancies in U.S. Women: A Systematic Review

Each year, nearly one-half of all pregnancies in the United States are unintended. Risk factors of unintended pregnancy have been studied without attention to whether the pregnancy was the woman's first unintended pregnancy or whether she had had more than one. Little is known about the prevalence, incidence, and risk factors for multiple unintended pregnancies. The purpose of this paper is to present a systematic review of the extant literature on the risk factors for multiple unintended pregnancies in women in the United States, and whether these factors are specific to multiple unintended pregnancies.

PubMed, PsychInfo, CINAHL, Web of Science, and JSTOR databases were searched for empirical research studies performed after 1979, in the United States, with a primary outcome of multiple unintended pregnancies. Articles that did not establish the intendedness of the studied pregnancies were excluded.

Seven studies were identified. For multiple unintended pregnancies, incidence rates ranged from 7.4 to 30.9 per 100 person-years and prevalence rates ranged from 17% to 31.6%. Greater age; identifying as Black or Hispanic; nonvoluntary first intercourse, particularly at a young age; sex trade involvement; and previous abortion were found to be associated with multiple unintended pregnancies. Use of intrauterine devices or combined oral contraceptives were found to decrease the risk of multiple unintended pregnancies.

This review suggests a small number of modifiable factors that may be used to better predict and manage multiple unintended pregnancies.