The initial prenatal visit is important in evaluation and assessment of risk during the pregnancy and should take place as early in the pregnancy as possible, preferably in the first trimester. Information of vital importance includes maternal medical and obstetric history, physical examination, and key laboratory findings.
Extremes of maternal age increase risks of maternal or fetal morbidity and mortality. Adolescents are at increased risk for preeclampsia–eclampsia, intrauterine growth restriction, and maternal malnutrition.
Women of increasing age at the time of delivery are at higher risk for preeclampsia, diabetes, and obesity, as well as other medical conditions. An increased risk of caesarean section, stillbirth, and placenta accreta are noted in women with advanced maternal age.
The risk of fetal aneuploidy increases with increasing age; the American College of Obstetricians and Gynecologists (ACOG), however, has recommended that maternal age of 35 years no longer be used as a cutoff to determine who is offered screening and who is offered invasive testing. Instead, patient counseling regarding options followed by maternal serum screening, ultrasound, and/or invasive testing, depending on patient's wishes, should occur.
It is important to differentiate spontaneous pregnancy from that resulting from assisted reproductive technologies (ART). Use of ART increases the risks of perinatal mortality (both stillbirths and early neonatal deaths), multifetal gestation, preterm birth (both singletons and multiples), congenital anomalies, and low birth weight.
Many medical disorders can complicate the pregnancy course for the mother and thus the fetus. It is important that these diseases and their severity be addressed before conception if possible. During pregnancy, the patient may require aggressive management and additional visits and testing to follow the course of the disease, in addition to possible consultation or management of a high-risk specialist. Table 12–2 lists some of the most important disorders that may complicate pregnancy.
Table 12–2. Some Maternal Diseases, Disorders, and Other Complications of Pregnancy. ||Download (.pdf)
Table 12–2. Some Maternal Diseases, Disorders, and Other Complications of Pregnancy.
Pulmonary disease (asthma, sarcoidosis)
Connective tissue disordersMaternal cancer
Blood disorders (anemia, coagulopathy, hemoglobinopathy)
A detailed family history is helpful in determining any increased risk of heritable disease states (eg, Tay-Sachs, cystic fibrosis, sickle cell disease) that may affect the mother or fetus during the pregnancy or the fetus after delivery. Other relevant findings includes family history of thromboembolism, birth defects (particularly cardiac anomalies), and medical history of first-degree relatives (particularly diabetes).
Population screening for certain inheritable genetic diseases is not cost effective because of the relative rarity of those genes in the general population. However, many genetic diseases affect certain ethnicities in disproportionate amounts, allowing cost-effective screening of those particular groups. Table 12–3 lists several common inheritable genetic diseases for which screening is possible. It includes the group at risk as well as the method of screening.
Table 12–3. Common Inheritable Genetic Diseases. ||Download (.pdf)
Table 12–3. Common Inheritable Genetic Diseases.
|Disease||Population at Increased Risk||Method of Testing|
|Alpha thalassemia||Chinese, Southeast Asian, African|
|β thalassemia||Chinese, Southeast Asians, Mediterraneans, Pakistanis, Bangladeshis, Middle Easterners, African|
|Bloom's syndrome||Ashkenazi Jews||Mutation analysis|
|Canavan's disease||Ashkenazi Jews||Mutation analysis|
|Cystic fibrosis||North American Caucasians of European ancestry, Ashkenazi Jews||Mutation analysis|
|Familial dysautonomia||Ashkenazi Jews||Mutation analysis|
|Fanconi's anemia||Ashkenazi Jews||Mutation analysis|
|Gaucher's disease||Ashkenazi Jews||Mutation analysis|
|Niemann-Pick disease||Ashkenazi Jews||Mutation analysis|
|Sickle cell disease and other structural hemoglobinopathies||African Americans, Africans, Hispanics, Mediterranean, Middle Easterners, Caribbean Indians|
|Tay-Sachs||Ashkenazi Jews, French Canadians, Cajuns||Enzyme and mutation analysis|
A diagnosis of recurrent abortion is made after 3 or more consecutive spontaneous losses of a pregnancy before 20 weeks' gestation. Recurrent abortion is best investigated before another pregnancy occurs; workup can be initiated after 2 losses. If the patient is currently pregnant, however, as much of the workup as possible should be performed.
- Karyotype of abortus specimen
- Parental karyotype
- Survey for cervical and uterine anomalies
- Screening for hormonal abnormalities (ie, hypothyroidism)
- Infectious disease evaluation of the genital tract
The association between inherited thrombophilias and recurrent pregnancy loss is unclear; thus the testing for these is currently not recommended in the clinical setting. Screening for antiphospholipid antibodies (acquired thrombophilia) may be appropriate.
Previous Stillbirth or Neonatal Death
A history of previous stillbirth or neonatal death should trigger an immediate investigation regarding the conditions or circumstances surrounding the event. If the demise was the result of a nonrecurring event, such as cord prolapse or traumatic injury, then the present pregnancy has a risk approaching the background risk. However, stillbirth or neonatal death may suggest a cytogenetic abnormality, structural malformation syndrome, or fetomaternal hemorrhage. Review of records, including autopsy, placental pathology, and karyotype if obtained, is vital. As with fetal loss, the association of unexplained stillbirth with inherited thrombophilias is unclear and testing is not recommended, although a maternal thrombophilia workup may be considered with stillbirth in the setting of severe placental thrombosis or infarcts, significant fetal growth restriction, or in the patient with a history of thrombosis.
Previous Preterm Delivery
A history of preterm birth confers an increased risk of early delivery in subsequent pregnancies. Furthermore, the risk of a subsequent preterm birth increases as the number of prior preterm births increases, and the risk decreases with each subsequent birth that is not preterm. The recurrence risk also rises as the gestational age of the previous preterm delivery decreases. Despite intense investigation, the incidence of preterm delivery has slightly increased in the United States, due in large measure to medical intervention producing indicated preterm deliveries. Eighty-five percent of preterm deliveries occur between 32 and 36 6/7 weeks, and they carry minimal fetal or neonatal morbidity. The remaining 15% of preterm deliveries, however, account for nearly all of the perinatal morbidity and mortality. Common causes of perinatal morbidity in premature infants include respiratory distress syndrome, intraventricular hemorrhage, bronchopulmonary dysplasia, necrotizing enterocolitis, sepsis, apnea, retinopathy of prematurity, and hyperbilirubinemia. Preterm deliveries can be divided into 2 types: spontaneous and indicated, with indicated preterm deliveries caused by medical or obstetric disorders that place the mother and/or fetus at risk. The clinical risk factors most often associated with spontaneous preterm birth include history of previous preterm birth, genital tract infection, nonwhite race, multiple gestation, bleeding in the second trimester, and low prepregnancy weight. Recent multicenter trials have shown that progesterone in the form of 17α-hydroxyprogesterone caproate, given as weekly injections of 250 mg beginning in the second trimester, can decrease the risk of preterm delivery in patients with a history of prior spontaneous preterm delivery.
Rh Alloimmunization or ABO Incompatibility
All pregnant patients should undergo an antibody screen at the first prenatal visit. Those patients who are Rh (D)–negative with no evidence of anti-D alloimmunization should receive Rh (D) immunoglobulin (RhoGAM; Ortho-Clinical Diagnostics, Rochester, NY) 300 μg at 28 weeks of gestation. Patients who are Rh (D) sensitized can be followed with maternal titers and/or amniocentesis for fetal blood typing, followed by either serial amniocentesis for ΔOD450 or serial middle cerebral artery peak systolic velocity measurements, as well as fetal blood sampling via cordocentesis.
Previous preeclampsia–eclampsia increases the risk for hypertension in the current pregnancy, especially if underlying chronic hypertension or renal disease is present.
Previous Infant with Genetic Disorder or Congenital Anomaly
A woman with a previous history of a fetus with a chromosomal abnormality is a frequent indication of cytogenetic testing, although this may be preceded by first- or second-trimester screening and anatomy ultrasound (US). The rate of recurrence depends on the abnormality.
A teratogen is any substance, agent, or environmental factor that has an adverse effect on the developing fetus. Whereas malformations caused by teratogen exposure are relatively rare, knowledge of exposure can aid in the diagnosis and management.
Alcohol, antiseizure medications (phenytoin, valproic acid, etc.), lithium, mercury, thalidomide, diethylstilbestrol (DES), warfarin, isotretinoin, and so forth.
Cytomegalovirus, Listeria, rubella, toxoplasmosis, varicella, Mycoplasma, and so forth.
It is believed that medical diagnostic radiation delivering less than 0.05 Gy (5 rad) to the fetus has no teratogenic risk.
Physical examination is important not only during the initial visit, but also throughout the pregnancy. Collection of maternal height and weight information allows for calculation of maternal body mass index, useful in risk assessment for many pregnancy abnormalities. In addition, weight gain is followed throughout the pregnancy, also a useful parameter for several risk factors in pregnancy. Vital sign abnormalities can lead to the diagnosis of many key obstetric complications. Fever, defined as a temperature of 100.4°F or greater, can be a sign of chorioamnionitis. Signs or symptoms of chorioamnionitis should be assessed, and, if chorioamnionitis is suspected, amniocentesis for microscopy and culture should be considered. Depending on clinical correlation, delivery may be necessary. Maternal tachycardia can be a sign of infection, anemia, or both. Isolated mild tachycardia (>100 beats/min) should be evaluated and followed up, as should maternal tachyarrhythmias. Maternal heart rate is noted to increase normally in pregnancy, however. The normal pattern of maternal blood pressure readings is a decrease from baseline during the first trimester, reaching its nadir in the second trimester, and slightly rising in the third trimester, although not as high as the baseline levels. Repeated blood pressure readings of 140/90 mm Hg taken 6 hours apart should be considered evidence of preeclampsia or gestational hypertension. Increases in systolic and diastolic blood pressure, although no longer part of the definition, may also be an indication of development of pregnancy-related hypertensive disease. The rest of the physical examination should be performed during the initial visit and focused examination during each visit. Fundal height measurements and fetal heart tone checks should also be performed.
At the first prenatal visit, a clean-catch urine culture and sensitivity should be performed. Any growth should be treated with the appropriate antibiotics. At all subsequent visits, urine dipstick testing to screen for protein, glucose, leukocyte esterase, blood, or any combination of markers is useful in identifying patients with a change in baseline urinary composition.
Screening tests during the initial visit include testing for rubella, rapid plasma reagin, hepatitis B, blood type, HIV, gonorrhea, and Chlamydia, and Pap smear.
American College of Obstetricians and Gynecologists. Inherited Thrombophilias in Pregnancy. ACOG Practice Bulletin No. 113. Washington, DC: American College of Obstetricians and Gynecologists; 2010.
American College of Obstetricians and Gynecologists. Screening for Fetal Chromosomal Anomalies. ACOG Practice Bulletin No. 77. Washington, DC: American College of Obstetricians and Gynecologists; 2007 (Reaffirmed 2008).
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