The first prenatal visit should occur as early as possible
after the diagnosis of pregnancy and should include the following: history,
physical examination, laboratory tests, advice to patients, and tests and
procedures.
Ask the patient's age, ethnic background, and occupation.
Gather information about onset of LMP and its normality, possible conception
dates, bleeding after LMP, medical history, all prior pregnancies (duration,
outcome, and complications), and symptoms of present pregnancy. Discuss with the
patient her nutritional habits as well as any use of caffeine, tobacco, alcohol,
or drugs (Table 18–1). Determine whether there is any family history of
congenital anomalies and heritable diseases, a personal history of childhood
varicella, or prior sexually transmitted diseases (STDs) or risk factors for HIV
infection.
Physical Examination
Height, weight, and blood pressure should be measured, and
a general physical examination should be done. Abdominal and pelvic examination
should include the following: (1) estimate of uterine size or measure fundal
height; (2) evaluation of bony pelvis for symmetry and adequacy; (3) evaluation
of cervix for structural anatomy, infection, effacement, dilation; (4) detection
of fetal heart sounds by Doppler device after 10 weeks or fetoscope after 18
weeks.
Laboratory Tests
Urinalysis, culture of a clean-voided midstream urine
sample, complete blood count with red cell indices, serologic test for syphilis,
rubella antibody titer, history of varicella infection, blood group, Rh type,
atypical antibody screening, and hepatitis B surface antigen (HBsAg) evaluation.
HIV screening should be offered to all pregnant women. Cervical cultures are
usually obtained for Neisseria gonorrhoeae and chlamydia, along with a
Papanicolaou smear of the cervix. All black women should have sickle cell
screening.
Women of African, Asian, or Mediterranean ancestry with anemia or low
mean corpuscular volume (MCV) values should have hemoglobin electrophoresis
performed to identify abnormal hemoglobins (Hb S, C, F, -thalassemia, -thalassemia). Tuberculosis skin testing is
indicated for high-risk immigrant and local populations. Genetic counseling with
the option of chorionic villus sampling or genetic amniocentesis should be
offered to all women who will be 35 years of age or older at delivery and those
who have had prior offspring with chromosomal abnormalities. Noninvasive first
trimester screening for Down syndrome by ultrasonographic nuchal translucency
and serum levels of PAPP-A (pregnancy-associated plasma protein A) and free subunit of hCG can also be
offered. Blood screening for Tay-Sachs and Canavan disease is offered to Jewish
women with Jewish partners (especially those of Ashkenazi descent), and couples
of French-Canadian or Cajun ancestry should also be screened as possible
Tay-Sachs carriers. Screening for cystic fibrosis is offered to all pregnant
women. Hepatitis C antibody screening should be offered to pregnant women who
are at high risk for infection.
Pregnant women who work in medical-dental health care or
the police and fire departments and those who are household contacts of a
hepatitis B virus carrier or a hemodialysis patient and are HBsAg-negative at
prenatal screening are at high risk for acquiring hepatitis B. They should be
vaccinated during pregnancy.
Advice to Patients
Prenatal Visits
Prenatal care should begin early and maintain a schedule of
regular prenatal visits: 0–28 weeks, every 4 weeks; 28–36 weeks, every 2 weeks;
36 weeks on, weekly.
Diet
- Eat a balanced diet containing the major food groups.
- Take prenatal vitamins with iron and folic acid.
- Expect to gain 20–40 lb. Do not diet to lose weight
during pregnancy.
- Decrease caffeine intake to 0–1 cup of coffee, tea, or
caffeinated cola daily.
- Avoid eating raw or rare meat or fish suspected of
elevated levels of mercury.
- Eat fresh fruits and vegetables and wash them before
eating.
Medications
Do not take medications unless prescribed or authorized by
your provider.
Alcohol and Other Drugs
Abstain from alcohol, tobacco, and all recreational
("street") drugs. No safe level of alcohol intake has been established for
pregnancy. Fetal effects are manifest in the fetal alcohol syndrome,
which includes growth restriction, facial abnormalities, and serious central
nervous system dysfunction. These effects are thought to result from direct
toxicity of ethanol itself as well as of its metabolites such as acetaldehyde.
Characteristic findings include shortened palpebral fissures, low-set ears,
midfacial hypoplasia, a smooth philtrum, a thin upper lip, microcephaly, mental
retardation, and attention deficit disorder. Skeletal and cardiac abnormalities
may also be seen.
Cigarette smoking results in fetal exposure to carbon
monoxide and nicotine, and this is thought to eventuate in a number of adverse
pregnancy outcomes. An increased risk of abruptio placentae, placenta previa,
and premature rupture of the membranes is documented among women who smoke.
Premature delivery occurs 20% more frequently among smoking pregnant women, and
the birth weights of their infants are on average 200 g lower than infants of
nonsmokers. Women who smoke should quit smoking or at least reduce the number of
cigarettes smoked per day to as few as possible. Pregnant women should also
avoid exposure to environmental smoke ("passive smoking").
Sometimes compounding the above effects on pregnancy
outcome are the independent adverse effects of illicit drugs. Cocaine use in
pregnancy is associated with an increased risk of premature rupture of
membranes, preterm delivery, placental abruption, intrauterine growth
restriction, neurobehavioral deficits, and sudden infant death syndrome. Similar
adverse pregnancy effects are associated with amphetamine use, perhaps
reflecting the vasoconstrictive potential of both amphetamines and cocaine.
Adverse effects associated with opioid use include intrauterine growth
restriction, prematurity, and fetal death.
X-Rays and Noxious Exposures
Avoid x-rays unless essential and approved by a physician
and with shielding. Inform your dentist and your providers that you are
pregnant. Avoid chemical or radiation hazards. Avoid excessive heat in hot tubs
or saunas. Avoid handling cat feces or cat litter. Wear gloves when
gardening.
Rest and Activity
Obtain adequate rest each day. Abstain from strenuous
physical work or activities, particularly when heavy lifting or weight bearing
is required. Exercise regularly at a mild to moderate level. Avoid exhausting or
hazardous exercises or new athletic training programs during pregnancy. Heart
rate should be kept below 140 beats/min during exercise.
Birth Classes
Enroll with your partner in a childbirth preparation class
well before your due date.
Tests & Procedures
Each Visit
Weight, blood pressure, fundal height, fetal heart rate are
measured, and a urine specimen is obtained and tested for protein and glucose.
Review any concerns the patient may have about pregnancy, health, and
nutrition.
6–12 Weeks
Confirm uterine size and growth by pelvic examination.
Document fetal heart tones (audible at 10–12 weeks of gestation by Doppler).
Perform transvaginal chorionic villus sampling between 10 and 12 weeks when
indicated or screening for trisomy 18, 21, and cardiac defects using nuchal
translucency measurement on sonography, free -hCG, and PAPP-A at 11–13 weeks.
12–18 Weeks
Genetic counseling should be offered for women age 35 years
or older at delivery and for those with a family history of congenital anomalies
or a previous child with a chromosomal abnormality, metabolic disease, or neural
tube defect. Amniocentesis is performed as indicated and requested by the
patient.
12–24 Weeks
Fetal ultrasound examination to determine pregnancy dating
and evaluate fetal anatomy is done (see ultrasound); (see ultrasound). An
earlier examination provides the most accurate dating, and a later examination
demonstrates fetal anatomy in greater detail. The best compromise is at 18–20
weeks of gestation.
16–20 Weeks
Maternal serum alpha-fetoprotein testing is offered to all
women to screen for neural tube defects. In some states, such testing is
mandatory. Serum alpha-fetoprotein is sometimes combined with measurement of
estriol and hCG (triple screen) or inhibin A (quad screen) for the detection of
fetal Down syndrome. The results of these analyses may be combined with first
trimester values as part of "integrated" aneuploidy screening.
20–24 Weeks
Instruct patient in symptoms and signs of preterm labor and
rupture of membranes. Consider cervical length measurement by ultrasound after
18 weeks with history of prior preterm delivery (> 2.5 cm is normal).
24 Weeks to Delivery
Ultrasound examination is performed as indicated.
Typically, fetal size and growth are evaluated when fundal height is 3 cm less
than or more than expected for gestational age. In multiple pregnancies,
ultrasound should be performed every 4 weeks to evaluate for discordant
growth.
26–28 Weeks
Screening for gestational diabetes by a 50-g glucose load
(Glucola) and a 1-hour post-Glucola blood glucose determination. Abnormal values
should be followed up with a 3-hour glucose tolerance tes.
28 Weeks
If initial antibody screen is negative, repeat antibody
testing for Rh-negative patients, but result is not required before
Rho(D) immune globulin is administered.
28–32 Weeks
Repeat the complete blood count to evaluate for anemia of
pregnancy.
28 Weeks to Delivery
Determine fetal position and presentation. Question the
patient at each visit for symptoms or signs of preterm labor or rupture of
membranes. Assess maternal perception of fetal movement at each visit.
Antepartum fetal testing is performed as medically indicated.
36 Weeks to Delivery
Repeat syphilis and HIV testing, cervical cultures for N
gonorrhoeae, and Chlamydia trachomatis in at-risk patients. Discuss
with the patient the indicators of onset of labor, admission to hospital,
management of labor and delivery, and options for analgesia and anesthesia.
Weekly cervical examinations are not necessary unless indicated to assess a
specific clinical situation. Elective delivery (whether by induction or cesarean
section) prior to 39 weeks of gestation requires confirmation of fetal lung
maturity.
The CDC has recommended universal prenatal culture-based
screening for group B streptococcal colonization in pregnancy. A single standard
culture of the distal vagina and anorectum is collected at 35–37 weeks. No
prophylaxis is needed if the screening culture is negative. Patients whose
cultures are positive receive intrapartum penicillin prophylaxis with labor.
Patients with risk factors such as a previous infant with invasive group B
streptococcal disease, or group B streptococcal bacteriuria during the
pregnancy, or delivery at less than 37 weeks of gestation also receive
intrapartum prophylaxis. Patients whose cultures at 35–37 weeks were not done or
whose results are not known receive prophylaxis only with the risk factors of
intrapartum temperature greater than 38 °C or membrane rupture greater than 18
hours.
The routine recommended regimen for prophylaxis is
penicillin G, 5 million units intravenously as a loading dose and then 2.5
million units intravenously every 4 hours until delivery. In penicillin-allergic
patients not at high risk for anaphylaxis, 2 g of cefazolin can be given
intravenously as an initial dose and then 1 g intravenously every 8 hours until
delivery. In patients at high risk for anaphylaxis, use vancomycin 1 g
intravenously every 12 hours until delivery or, after confirmed susceptibility
testing of group B streptococcal isolate, clindamycin 900 mg intravenously every
8 hours or erythromycin 500 mg intravenously every 6 hours until delivery.
41 Weeks and Beyond
Examine the cervix to determine the probability of
successful induction of labor. Based on this, induction of labor is undertaken
if the cervix is favorable (generally, cervix 2 cm dilated 50% effaced, vertex at –1 station,
soft cervix, and midposition); if unfavorable, antepartum fetal testing is
begun.
Resources:
Current Medical Diagnosis &
Treatment 2008
Stephen J. McPhee, Maxine A. Papadakis, and Lawrence M.
Tierney, Jr., Eds.
Ralph Gonzales, Roni Zeiger, Online Eds.
