Prenatal Care

·         Estrogen activates oxytocin secretion and myometrial gap junction formation.

Progesterone suppresses production of maternal lymphocytic cytokines, which contribute to immune rejection of the fetus. Progesterone produced by the corpus luteum is essential for pregnancy maintenance until the eighth week. Progesterone suppositories are prescribed during the first 8 weeks of gestation in women with suspected corpus luteum deficiency.

hCG regulates fetal testicular testosterone production, which is critical for the development of male external genitalia. Elevated hCG is the most sensitive serum marker for Down syndrome. Abnormally high levels of hCG are seen in multiple gestation (twins).

hPL induces lipolysis, which provides energy for the mother in the form of fatty acids. hPL also provides energy for the fetus by elevating ketone levels.

Prolactin is produced not only by the decidual tissue of the uterus, but also by the maternal and fetal pituitary glands. Lactation does not occur during pregnancy because estrogen inhibits the action of prolactin on the breast.

Low levels of estriol are associated with placental sulfatase deficiency.

 Anencephaly contributes to lack of ACTH production; therefore, the fetal adrenal cortex is not stimulated properly to convert pregnenolone to DHEA and DHEAS, which are essential in the production of estriol.

·         The differential diagnosis of recurrent spontaneous abortions in women includes deficiencies of protein C and protein S, and the presence of the lupus anticoagulant, which is part of the anti-phospholipid syndrome.

·         It is not uncommon for patients with osteogenesis imperfecta type II—the lethal form—to have dozens of fractures before birth. Osteogenesis imperfecta types I and III, which are compatible with life and may cause blue scleras (type I), are often not detectable before birth.

·         Anencephaly is, of course, incompatible with life and is the only condition for which a termination of pregnancy is generally permissible at any gestational age.

The incidence of neural tube defects in the general population is approximately 1.4 to 2.0/1000. It is a multifactorial defect and is not influenced by maternal age. Women who have a previously affected child have a neural tube defect recurrence risk of about 3 to 4%. A chorionic villus sampling will determine a fetus’s chromosomal makeup but will give no information regarding AFP levels or risk for a neural tube defect. Hyperthermia at the time of neural tube formation in the embryo, as can occur with maternal fever or sauna baths, can increase the relative risk of a neural tube defect up to sixfold.

·         Vaccines for measles and mumps are generally considered to be contraindicated in pregnancy as these are live viruses, although the rubella vaccine, which is known to have been administered inadvertently to over 1000 pregnant women, has never caused a problem and in fact can be used in selected circumstances of exposure. No cases of congenital rubella syndrome have been reported in this group of patients.

Administration of rabies vaccine is unaffected by pregnancy.

Immunization for yellow fever is recommended before travel to a high-risk area. ( confusion ??)

·         Moderate consumption of coffee has not been associated with any fetal risks. Consumption of more than five cups of coffee a day has been shown to be associated with a slightly increased risk of spontaneous abortion in some studies. Cocaine use has been associated with an increased incidence of placental abruption and a constellation of congenital anomalies (skull defects, disruptions in urinary tract development, limb defects, and cardiac anomalies). Marijuana has not been associated with any adverse fetal effects. Lysergic acid diethylamide (LSD) has not been found to be a human teratogen. Tobacco use has been associated with a number of adverse pregnancy outcomes including spontaneous abortion, preterm labor, growth restriction, placental abruption, placenta previa, and attention deficit disorder and behavior and learning problems.

·         Chorionic villus sampling performed at a gestational age of less than 9 weeks has been associated with fetal limb reduction defects.

·         A high level of hCG in the second trimester is the most sensitive marker for Down syndrome. A high level of hCG in the first trimester is suggestive of molar pregnancy. hCG is part of the quadruple screen in the second trimester, not the first trimester. A low level of hCG is suggestive of ectopic pregnancy. hCG stimulates production of TSH, not TRH, leading to hyperthyroidism.

·         Ultrasound examination in the first trimester provides the most accurate dating. Measurement of the crown-rump length (CRL) is accurate to within 5 to 7 days of the actual gestational age. Second- and third-trimester ultrasound uses several parameters for determining gestational age. These parameters include the biparietal diameter (BPD), the femur length (FL), and the abdominal circumference (AC). In the second trimester, the BPD is the most accurate but only to within 14 days of the actual gestational age. Measurements in the third trimester may have an error up to ±21 days of the actual gestational age.