- Clinical science
Prenatal care refers to the healthcare that women receive throughout pregnancy. Guidelines for routine prenatal care determine the scope and frequency of prenatal visits and screening. Prenatal visits aim to detect high-risk pregnancies and to monitor the course of pregnancy and fetal development. They involve recording the mother's medical history, consultations, physical and gynecological examinations, laboratory diagnostic analyses, and regular ultrasound screening. Prenatal care visits initially occur once monthly until the 28th gestational week, twice monthly between the 28th and 36th week, and weekly after the 36th week. This article covers the general principles of prenatal care, as well as some of the most important diagnostic methods routinely used for the care of pregnant women (i.e., Leopold's maneuvers, obstetric ultrasound).
Frequency of check-ups
- Until the 28th week of pregnancy: monthly
- From the 28th week until the 36th week: every two weeks
- From the 36th week until birth: every week
- In pregnancies, frequent visits are usually warranted.
Initial examination (∼ 10 weeks' gestation)
- Personal and family history, previous pregnancies
- Gynecological examination
- Blood pressure
Laboratory analysis: standard laboratory tests performed in all pregnant women during the first prenatal visit
- Complete blood count
- Hemoglobin: screening for anemia (often iron deficiency anemia)
- Blood typing (ABO and rhesus): screening for risk of hemolytic disease of the newborn
- Urine dipstick protein testing: screening for proteinuria (baseline value is vital for comparison with results in later pregnancy to rule out preeclampsia); performed during every prenatal visit
- Urine culture: screening for asymptomatic bacteriuria (see )
Screening for STIs
- (see )
- (Syphilis during pregnancy)
- Hepatitis B surface antigen testing (see and hepatitis B in pregnancy )
- Gonorrhea testing: in all patients < 25 years of age and ≥ 25 years with high risk of infection
- In all patients < 25 years of age and ≥ 25 years with high risk of infection (according to CDC and US Preventive Services Task Force guidelines)
- In all pregnant patients (according to the ACOG guidelines)
- Rubella and varicella antibody testing (unless there is evidence of immunity)
- PAP smear
- Ultrasound assessment of the estimated gestational age through the crown-rump length (see also )
- General advice for pregnant women
The following should be performed during each prenatal care visit regardless of pregnancy-related complaints and symptoms:
- Weight monitoring: to avoid fetal developmental problems (if weight gain is less than the recommended amount), fetal macrosomia, or maternal obesity (if weight gain is above normal)
- Blood pressure monitoring: early detection of
- : : battery of tests for the screening of chromosomopathies
- Physical examination
- Group B streptococcus screening performed between 36 0/7 and 37 6/7 weeks of gestation (vaginal and rectal swab for culture and gram staining) because colonization by this bacteria may cause and neonatal infection.
- Repeat Hb from the 24th week of pregnancy.
- 50-g, one-hour oral glucose challenge test (initial screening) at 24–28 weeks gestation
- Repeat rhesus screening: An unsensitized Rh(D)-negative women should receive anti(D)-immune globulin (see ).
- All pregnant women (regardless of age) should be offered noninvasive aneuploidy screening tests (before 20 weeks gestation)
- Possible tests:
- All pregnant women (regardless of age) should be given the alternative option to undergo invasive genetic testing; ( or )
- Pre-test counseling must be provided: inform the parents that screening is voluntary; explain the difference between screening and diagnostic tests, risk of false positive and false negative tests, explain option of terminating the pregnancy if aneuploidy is diagnosed
Noninvasive screening tests
|First-trimester combined screening|| |
11–13 weeks gestation
|Quad screen test||15–20 weeks gestation|| |
|Triple screen test||15–20 weeks gestation|
|Sequential integrated test||10–13 weeks gestation followed by 15–20 weeks gestation|
|Cell-free fetal DNA testing (cffDNA)|| |
From 10 weeks gestation onwards
Invasive diagnostic tests
|Chorionic villus sampling (CVS)|| || || |
|Amniocentesis|| || |
|Cordocentesis|| || |
- First: : bimanual examination of the fetal position; (longitudinal/oblique/transverse) and fundal height
- Second: : bimanual examination of the location of the fetal back (i.e., either on the mother's left or right side)
Third: : One hand grasps above the symphysis; in an attempt to determine if the presenting part of the fetus is engaged.
- In cases of cephalic presentation , the fetal head feels hard and ballotable; if the fetus is in a breech position, a soft and less movable rump can be felt.
- Fourth: : Bimanual determination of the location of the fetal brow and the degree of flexion of the fetus's head. Usually performed during the later stages of pregnancy when the fetus has entered the pelvic inlet.
|Week of pregnancy||Fundal height during pregnancy|
|12th||Just above the symphysis|
|20th||Between the symphysis and navel|
|32nd||Between the navel and xiphoid|
|36th||Peak: at the costal arch|
|40th||Two finger widths below the costal arch|
The following tests are performed into assess the risk of antenatal fetal death.
Nonstress test (NST): a noninvasive test () that measures FHR reactivity to fetal movements
- Indications: maternal medical conditions (e.g., gestational diabetes, preeclampsia) or fetal conditions (e.g., fetal heart defects, fetal growth restriction)
- Usually performed in the third trimester (after the 32nd gestational week)
A normal NST would show ≥ 2 FHR accelerations.
- Reactive nonstress test: if the nonstress test is normal
- Non-reactive nonstress test: if the NST is nonreactive (<2 FHR accelerations)
- Category II fetal heart rate tracing
- Contraction stress test (CST): measures FHR reactivity in response to uterine contractions
Biophysical profile (BPP): a noninvasive test that evaluates the risk of antenatal fetal death, usually performed after the 28th gestational week
- Measured parameters: each parameter receives a score of either 0 (abnormal) or 2 (normal) points (see table below).
|Biophysical profile scoring criteria|
|Parameter||Normal results (= 2 points)|
|Fetal movement|| |
|Fetal breathing|| |
|Amniotic fluid volume|| |
|Nonstress test|| |
- Suspected intrauterine growth restriction
- Pregnancy-induced hypertension in the current or a prior pregnancy
- Condition affecting a fetus that is small for gestational age, or intrauterine death
- Suspicious cardiotocography (CTG)
- Suspected fetal deformities or diseases
- Growth discordance in multiple pregnancies
|Uterine artery||Early diastolic notch|
Decline or loss of end diastolic flow velocity or negative flow
Fetal middle cerebral artery
|Increased diastolic flow velocity|