Pregnancy

Pregnancy is the period of time when a fetus develops inside a woman’s uterus and ends with the birth of the infant. Pregnancies typically involve a variety of clinical laboratory tests. The tests provide useful information from the time pregnancy is first considered through the initial days of the newborn’s life. Some of these tests are performed at specified times throughout the pregnancy. Others are ordered as needed to detect and address conditions or problems that arise during pregnancy. Still others are offered to women who have increased risks because of their age or lifestyle and, finally, certain tests are selectively chosen based on the personal and family medical histories of the woman and her partner.

The purposes of prenatal tests are to screen for and diagnose any existing problems that may affect the mother’s or baby’s health, identify and address problems as they arise, and assess the risk of a baby having a chromosomal or genetic abnormality. The tests generally require just a small sample of easily obtained blood, urine, or cervical cells.

The following pages contain information on many of these routine and some less routine tests. Your health care provider may recommend additional tests based on your medical history. Parents-to-be are encouraged to ask their health care providers why specific tests are being offered to them. Health care providers and reliable Internet sources, such as the March of Dimes and the U.S. Centers for Disease Control and Prevention, can help you understand the risks and benefits of each test.

Below is a table summarizing these tests:

Purpose	Test name	Why performed	When performed	Who performed on/Sample
Genetic tests for inherited diseases	Genetic testing for inherited diseases	Check carrier status for certain genetic diseases to determine risk of having a baby with such a disease	Pre-conception or 1st Trimester	Mother and father (blood sample)
	Genetic testing for hemoglobin disorders	Check carrier status for certain hemoglobin disorders to determine risk of having a baby with such a disease	Pre-conception or during pregnancy	Mother and father (blood sample)
	Cystic fibrosis carrier testing	Check carrier status for CF	Pre-conception or first trimester	Mother and father (blood sample)
Testing associated with health conditions of the mother that affect pregnancy	Immunity to rubella (German measles)	Check for immunity to the virus, which can cause birth defects	Pre-conception or first trimester	Mother (blood sample)
	Human immunodeficiency virus (HIV) antibody test	Check for HIV infection so steps can be taken to reduce likelihood of transmission to the baby	Pre-conception or first trimester; may be repeated in third trimester if at high risk	Mother (blood sample)
	Gonorrhea, chlamydia, and syphilis tests	Check for STD infections, which can cause miscarriage or infect the baby during delivery	Pre-conception or first trimester; may be repeated in third trimester if at high risk	Mother (cervical cells, urine or blood sample, depending on test)
	Pap smear	Detect abnormal cervical cells, inflammation, or STDs	Pre-conception or first trimester	Mother (cells from her cervicx)
	Hepatitis B screening	Detect Hepatitis B infection	Pre-conception or first trimester; may be repeated in the third trimester if at high risk	Mother (blood sample)
	Varicella zoster viral testing	Check for immunity to chicken pox, which can cause birth defects	Pre-conception or first trimester	Mother (blood sample)
	TORCH panel	Check for infection with toxoplasmosis and other infectious diseases that can cause birth defects	Pre-conception or first trimester, if infections suspected	Mother (blood sample)
	Bacterial vaginosis	Detect infection, which can cause pre-term labor and birth	Pre-conception or whenever symptoms experienced	Mother (vaginal secretions)
	Urine culture for bacteriuria	Detect bacterial infection in the urinary tract, which can lead to kidney infection or increased risk of pre-term delivery and low birth weight	First prenatal visit or between 12 and 16 weeks of pregnancy; may be repeated in third trimester	Mother (urine sample)
	Group B streptococcus	Detect infection, which can harm the baby during birth and infect the mother’s uterus, urinary tract, and any incision made during a cesarean section	Between weeks 35 and 37 of pregnancy	Mother (specimen from vaginal and rectal areas)
Monitoring of pregnancy	Pregnancy test	Confirm pregnancy	First trimester	Mother (blood sample)
	Urine screen for sugar and/or protein	Check for signs of kidney or bladder infection, gestational diabetes, or preeclampsia	Each prenatal visit	Mother (urine sample)
	Hemoglobin test	Check for anemia	Pre-conception and/or early in the first trimester; repeated in third trimester	Mother (blood sample)
	Antibody screen	Check for potential incompatibility in blood type between mother and fetus (such as Rh factor antibodies)	First trimester; repeated at week 28 of pregnancy	Mother (blood sample)
	Glucose challenge test/oral glucose tolerance test	Check for gestational diabetes	Between 24 and 28 weeks of pregnancy	Mother (blood sample)
	Platelet count	Detect a low count or other platelet problem; platelets are important for blood clotting in case of bleeding during delivery	Third trimester	Mother (blood sample)
Detection of fetal abnormalities or risk	First trimester Down syndrome screen	Assess risk of carrying a fetus with certain chromosomal abnormalities, such as Down syndrome	Usually between 10 weeks, 4 days and 13 weeks, 6 days of pregnancy	Mother (blood sample plus ultrasound)
	Triple marker or quad marker screen	Assess risk of carrying a fetus with certain chromosomal abnormalities and open neural tube defects	Between 15 and 20 weeks of pregnancy	Mother (blood sample)
	Chorionic villus sampling	Detect chromosomal disorders in the fetus	Between weeks 10 and 12 of pregnancy, if recommended	Mother (cells from the placenta)
	Amniocentesis	Detect certain birth defects and chromosomal abnormalities	Between 15 and 20 weeks of pregnancy, if recommended	Mother (amniotic fluid)
	Cordocentesis	Detect chromosome abnormalities, blood disorders, and certain infections	Between weeks 18 and 22 of pregnancy, if recommended	Mother/fetus (fetal blood sample obtained from vein in the umbilical cord)
Fetal maturity/readiness for birth	Amniocentesis	Check fetal lung development	After week 32 of pregnancy if risk of pre-term delivery	Mother (amniotic fluid)
Fetal maturity/readiness for birth	Fetal fibronectin (fFN)	Detect fFN, negative result is highly predictive that pre-term delivery will NOT occur in the next 7-14 days	Between week 26 and 34 of pregnancy, if having symptoms	Mother (cervical or vaginal fluid sample)