Some common viruses, bacteria, and parasites that invade the normal human can infect the fetoplacental unit by blood-borne transmission. Others may infect locally through genitourinary infection or colonization. However, despite the numerous infections acquired in pregnancy and discussed in Chapters 64 and 65, these uncommonly cause early abortion.
Some disorders are possibly linked with higher rates of early pregnancy loss and are discussed in their respective chapters. Prominent risks are associated with poorly controlled diabetes mellitus, obesity, thyroid disease, and systemic lupus erythematosus. In these and others, inflammatory mediators may be an underlying theme (Kalagiri, 2016; Sjaarda, 2017). Although thrombophilias were initially linked to various pregnancy outcomes, most putative associations have been refuted (American College of Obstetricians and Gynecologists (2017e).
herapeutic doses of radiation are undeniably abortifacient. Doses that cause abortion are not precisely known, but suggested parameters are found in Chapter 46 (p. 906). Similarly, the efects of chemotherapy exposure in causing abortion are not well deined (Chap. 12, p. 242). Particularly worrisome are women with an ongoing pregnancy after early exposure to methotrexate, described later (p. 361). Of cancer survivors, those who were treated with abdominopelvic radiotherapy or chemotherapy may later be at greater risk for miscarriage, as discussed in Chapter 63 (p. 1192).
The risk of miscarriage caused by surgery is not well studied. But, as discussed in Chapter 46 (p. 901), uncomplicated surgical procedures performed during early pregnancy are unlikely to increase the abortion risk (Mazze, 1989). Of indications, ovarian tumors can generally be resected without inciting miscarriage. An important exception involves early removal of the corpus luteum or the ovary in which it resides. If performed before 10 weeks' gestation, supplemental progesterone should be given, and supplementation is enumerated in Chapter 63 (p.i1198).
Trauma seldom causes first-trimester miscarriage, and although Parkland Hospital is a busy trauma center, this is an infrequent association. Major trauma-especially abdominalcan cause fetal loss, but is more likely as pregnancy advances (Chap. 47, p. 925).
Sole deficiency of one nutrient or moderate deiciency of all does not appear to increase risks for abortion. Even in extreme cases-for example, hyperemesis gravidarum-abortion is rare. Dietary quality may play a role, as miscarriage risk may be reduced in women who consume a diet rich in fruits, vegetables, whole grains, vegetable oils, and ish (Gaskins, 2015). With regard to maternal weight, underweight is not associated with a greater miscarriage risk (Balsells, 2016). However, as noted in Chapter 48 (p. 938), obesity does raise pregnancy loss rates.
Lifestyle choices reputed to be associated with a higher miscarriage risk are most often related to chronic and especially heavy use oflegal substances. he most commonly used is alcohol, with its potent teratogenic efects discussed in Chapter 12 (p. 239). That said, an increased miscarriage risk is only seen with regular or heavy use (Avalos, 2014; Feodor Nilsson, 2014).
Approximately 10 percent of pregnant women admit to cigarette smoking (Centers for Disease Control and Prevention, 2016). It seems intuitive that cigarettes could cause early pregnancy loss (Pineles, 2014). Adverse efects of illicit drugs areidiscussed in Chapter 12 (p. 249).