632 Obstetrics and Gynecology Board Review •••
❍ Does amphetamine use in pregnancy cause congenital abnormalities?
Amphetamine use in pregnancy has not been associated with congenital abnormalities; however, its use correlates
to a reduction in birth weight, prematurity, postpartum hemorrhage, and retained placenta. Because of anorectic
impact of the drug, amphetamines may severely affect maternal nutrition.
❍ How does cocaine affect pregnancy?
The most common complication caused by cocaine during pregnancy is abruptio placentae due to vasoconstriction
and extreme high blood pressures. In addition, brain anomalies, intestinal atresia, congenital heart defects, and limb
reductions have been described. Cocaine may cause these effects by vasoconstrictions and subsequent infarction.
❍ What is the neonatal abstinence syndrome, and what agents cause it?
It is caused by maternal heroin addiction or maternal methadone treatment during pregnancy. It results from
neonatal withdrawal and consists of tremulousness, hyper-reflexia, high pitch cry, sneezing, sleepiness, tachypnea,
yawning, sweating, fever, and seizures. The onset of symptoms is at birth.
❍ What is fetal alcohol syndrome?
Infants suffer from IUGR, mental retardation, and develop characteristic facies, which consists of short palpebral
fissures, a flat midface, a thin upper lip, and hypoplastic philtrum.
❍ At what time during gestation is the fetus most susceptible to alcohol toxicity?
Probably in the second and third trimesters. In a study of 60 women, those who were heavy drinkers but stopped
after the first trimester had children with normal mentation and behavioral patterns.
❍ Your 28-year-old pregnant patient expresses concerns about the ultrasound examination you have
prescribed. How do you counsel her?
Ultrasound has no documented harmful effect on developing fetuses with the use of current ultrasound techniques.
High-level ultrasound energy could potentially cause harm to the fetus by two mechanisms—thermal damage and
cavitation. However, these effects are not seen at the low levels of ultrasound energy used during diagnostic studies.
❍ What recommendations would you make to a woman who requires a magnetic resonance imaging (MRI)
study during pregnancy?
MRI has not been shown to be harmful in pregnancy. However, based on a lack of evidence that supports the
safety of MRI during pregnancy, the National Radiological Protection Board has recommended that women in the
first 3 months of pregnancy be excluded from MRI examinations. There is no evidence to recommend termination
of pregnancy after an inadvertent first trimester exposure.
❍ What is the time of gestation during which a fetus is most susceptible to the effects of ionizing radiation?
The fetus is most susceptible to radiation between 8 and 15 weeks of gestation. Before 8 weeks if the exposure does
not result in a spontaneous abortion, the fetus will be unaffected. Between 16 and 25 weeks postfertilization, the
fetus is less vulnerable to radiation effects. After the 26th week of pregnancy, the radiation sensitivity of the unborn
baby is similar to that of a newborn.
❍ How would a significant radiation exposure affect a fetus?
Doses of >100 rads (cGy) have been associated with microcephaly, which may or may not be associated with
mental retardation. Growth retardation is also seen in exposed fetuses. From epidemiologic and animal studies, it
does not appear that exposures of <10 rads could affect a pregnancy at any gestational age.