Excessive cafeine consumption-not well defined-has been associated with a higher abortion risk. Reports link heavy intake of approximately ive cups of cofee per dayabout 500 mg of cafeine-with a slightly greater abortion risk (Cnattingius, 2000; Klebanof, 1999). Studies of "moderate" intake-less than 200 mg daily-did not indicate increased risk (Savitz, 2008; Weng, 2008). In contrast, in one prospective cohort of more than 5100 gravidas, cafeine was linked to miscarriage but not in a dose-response relationship (Hahn, 2015). Currently, the American College of Obstetricians and Gynecologists (2016e) has concluded that moderate consumption likely is not a major abortion risk and that any associated risk with higher intake is unsettled.
Environmental toxins suggested to have a possible link to miscarriage include bisphenol A, phthalates, polychlorinated biphenyls, and dichlorodiphenyltrichloroethane (DDT) (Krieg, 2016). Even fewer studies implicate occupational exposures. In a follow-up of the Nurses Health Study II, Lawson and associates (2012) reported slightly increased miscarriage risks in nurses exposed to sterilizing agents, x-rays, and antineoplastic drugs. Also, a higher miscarriage risk was found for dental assistants exposed to more than 3 hours of nitrous oxide daily if there was no gas-scavenging equipment (Boivin, 1997).
Increasing paternal age is signiicantly associated with an greater risk for abortion (de La Rochebrochard, 2003). In the Jerusalem Perinatal Study, this risk was lowest before age 25 years, after which it progressively increased at 5-year intervals (Kleinhaus, 2006). The etiology of this association is not well studied, but chromosomal abnormalities in spermatozoa likely play a role (Sartorius, 2010).
his diagnosis is presumed when bloody vaginal discharge or bleeding appears through a closed cervical os during the first 20 weeks. This bleeding in early pregnancy must be diferentiated from that with implantation, which some women have at the time of their expected menses. Aside from this, almost one fourth of women develop bleeding during early gestation that may persist for days or weeks. It may be accompanied by suprapubic discomfort, mild cramps, pelvic pressure, or persistent low backache. Of symptoms, bleeding is by far the most predictive risk factor for pregnancy loss.
Even if miscarriage does not follow threatened abortion, rates of later adverse pregnancy outcomes are increased as shown in Table
Of these, highest risks are for preterm delivery. Weiss and coworkers (2004) noted greater risks for adverse outcomes in later pregnancy if early bleeding was heavy rather than light. Compared with those without bleeding, women with first-trimester bleeding in an initial pregnancy have higher recurrence rates in their second (Lykke, 2010).
TABLE 18-1. Adverse Outcomes That Are Increased in Women with Threatened Abortion
Placenta previa Preterm ruptured membranes Placental abruption Preterm birth Manual removal of placenta Low-birthweight infant Cesarean delivery Fetal-growth restriction
From Lykke, 2010; Saraswat, 2010; Weiss, 2004; Wijesiriwardana,s2006.