MFM Learn all you need to know about Maternal Fetal Medicine.

Maternal-Fetal Medicine (MFM) is a subspecialty of obstetrics and gynecology. A maternal-fetal medicine specialist, also known as a perinatologist, is an obstetrician who has completed further training called a fellowship. Currently, a maternal-fetal medicine fellowship is an additional 3 years of training after a 4 year OB/GYN residency.
Women are referred for many reasons. Dr. Weiss has extensive training in pregnancies with complications and potential for complications. Some examples include: multiple gestations, medical complications, increased risk for genetic complications, prior pregnancy complication and a suspicion of a fetal abnormality.
Ultrasound (sonography) is an essential component of Dr. Weiss’ specialty. Your doctor may ask him to perform a general fetal anatomical survey (Level 2 ultrasound) to confirm a normal appearing fetus. In addition, your doctor may refer you for genetic screening such as nuchal translucency measurement for Down syndrome risk assessment.
Dr. Weiss is board certified in both obstetrics and gynecology and maternal-fetal medicine. He has extensive training in both vaginal and cesarean deliveries. However, his practice is consultative. He will work with your doctor to establish a management plan. During the course of your pregnancy, you may see Dr. Weiss once or you may have multiple visits. However, your doctor will perform your delivery.
Ultrasound is a procedure which utilizes sound waves to create an image. The ultrasound image enables visualization of the mother’s uterus and cervix as well as the baby. Ultrasound is a way to identify structures of the developing baby including the organs such as the brain and heart as well as the face, hands, feet and gender. Ultrasound is a wonderful technology; however, not all abnormalities can be detected by ultrasound.
Ultrasound may be performed at different times during pregnancy. First trimester ultrasound imaging may be performed to confirm fetal viability, to establish dating or to perform a genetic screening test. Second trimester ultrasound imaging may be performed to evaluate the anatomy of the developing baby. This is typically performed between 18-20 weeks. Third trimester ultrasound imaging may be performed to evaluate fetal growth, amniotic fluid volume or fetal well-being.
Amniocentesis is a procedure performed to obtain a sample of the amniotic fluid surrounding the fetus. The procedure involves placement of a thin needle into the amniotic sac under continuous ultrasound guidance. Once in place, a small amount of fluid is removed. Genetic amniocentesis, typically performed between 15 and 20 weeks, is performed for genetic analysis to evaluate for a chromosomal abnormality such as Down syndrome. Testing for inherited genetic disorders such as cystic fibrosis, sickle cell anemia and Tay-Sachs may also be performed by amniocentesis. In addition, amniocentesis can be performed during evaluatiaon for open neural tube defects such as spina bifida and congenital fetal infections.
As with any invasive procedure, there are some risks associated with amniocentesis. In general, the pregnancy loss rate associated with amniocentesis is approximately 1/300. Minor complications which may occur include vaginal spotting or amniotic fluid leakage (1-2%) and infection (< 1/1000).
Chorionic villus sampling (CVS) is a procedure performed to obtain a sample of the placenta. It is performed in a similar fashion as amniocentesis. The procedure is typically performed between 10 and 13 weeks. It is performed to obtain genetic analysis for a chromosomal abnormality such as Down syndrome, cystic fibrosis, sickle cell anemia and Tay-Sachs. The advantage of CVS is the ability to obtain genetic information in the first trimester. However, CVS can not provide information regarding open neural tube defects.
As with any invasive procedure, there are some risks associated with chorionic villus sampling. In general, there is a 1/200-300 pregnancy loss rate associated with CVS.
Percutaneous Umbilical Blood Sampling (PUBS) is a procedure performed to obtain a sample of fetal blood. The procedure involves placement of a thin needle into the umbilical vein within the amniotic sac under continuous ultrasound guidance. Once in place, fetal blood can be removed and tested. This procedure can be performed to evaluate for a fetal genetic or chromosomal abnormality or fetal infection. However, it is most commonly performed to evaluate for severe fetal anemia or low fetal platelet values. The fetus may receive a blood and/or platelet transfusion while inside the uterus during this procedure. The procedure related loss rate has been reported to be less than 2%.
Preconceptional counseling is a session where Dr. Weiss and/or the genetic counselor will discuss your medical and obstetrical history as well as any laboratory information. Advice and recommendations regarding future pregnancies will be discussed.
There are several options to evaluate your risk for chromosomal abnormalities (aneuploidy). Down syndrome is a condition where there are three copies of chromosome 21 (trisomy 21). As a woman’s age increases, her risk for aneuploidy increases as well. Typically, women 35 years or older at the time of delivery are considered at increased risk for aneuploidy including Down syndrome. Despite the increased risk as age increases, 85% of Down syndrome pregnancies occur in women less than 35 years of age.
The goal of aneuploidy screening differs depending upon maternal age. The goal for women less than 35 is to detect pregnancies at higher risk for fetal aneuploidy. These women can then be offered diagnostic testing such as amniocentesis or chorionic villus sampling. The goal for women 35 years and older at delivery is to detect pregnancies with a lower risk for fetal aneuploidy in order to avoid an invasive diagnostic procedure.
Aneuploidy screening tests that include a combination of ultrasound and maternal blood testing are First Screen (also referred to as nuchal translucency screening) and Sequential Screening (combination of First Screen and second trimester serum screening). Aneuploidy screening involving only maternal blood include serum aneuploidy screening and circulating cell free DNA (ccfDNA) screening.
First Screen, Sequential Screen and serum aneuploidy screening revise a mother’s risk for certain chromosomal abnormalities such as Down syndrome utilizing a combination of factors including the maternal age, weight, gestational age, ultrasound measurements (not serum aneuploidy screening) and placental derived protein values. The ccfDNA screening isolates free floating maternal and placental DNA fragments. Once isolated, the DNA is amplified and the percentage of specific DNA is calculated. The Society for Maternal Fetal Medicine and American College of Obstetrics and Gynecology recommend that ccfDNA screening be offered as first line screening only for women who meet high risk criteria for fetal aneuploidy. Standard screening (First Screen, Sequential Screen or serum aneuploidy screening) should be first line screening methods for low risk women. However, the ccfDNA screening is available, should a woman in a low risk category desire that particular test.
It must be emphasized that screening tests and invasive testing should be individualized for each patient and situation.
CVS (chorionic villus sampling) and amniocentesis are examples of diagnostic tests for conditions like Down syndrome. That means they can tell you for sure whether the baby either has, or does not have, such a condition. Some patients prefer to get very definite or "black and white" information, like this. However, since these tests involve placing a thin needle into your uterus, there is a small risk that a miscarriage. Because of the concern about possibly triggering a miscarriage, some patients prefer to avoid these “needle tests”, unless absolutely necessary. In this situation, a screening test that gives a more accurate assessment of the chances of a problem with the baby may be suitable. Screening tests do not tell you whether the baby is healthy or whether the baby has a problem. There are currently two types of screening tests, standard screening (First Screen, Sequential Screening and second trimester serum aneuploidy screening) and circulating cell free DNA (ccfDNA) screening. The specific differences between these screening tests should be discussed at your visit. In general, the screening testing tells you what are the "odds" or chances of having a specific chromosomal abnormality.
Unfortunately, congenital abnormalities affecting babies' health are common. About 3% of all babies have some sort of physical or mental abnormality or limitation.
Chromosome abnormalities, such as Down syndrome or Trisomy 18, are often related to the age of the mother.
Cardiac abnormalities, such as "hole in the heart", occur in approximately eight in every 1,000 pregnancies (slightly less than 1%). Fortunately, many of these heart abnormalities are minor and do not require surgery. Some however are so serious that it may be necessary for your doctor to make special arrangements about where you deliver, and for your baby to undergo urgent heart surgery. If you have previously had a baby with a heart problem, or if someone in your family or your partner's family have had a baby with a heart problem, your chances of this happening may be significantly higher. In this situation, you should bring this to the attention of your doctor for further specific advice.
Spine and brain abnormalities, such as spina bifida, occur in approximately two in every 1,000 pregnancies. If you take folic acid supplementation prior to becoming pregnant, and during the first two months of pregnancy, your chances of these problems should be significantly lower. If you have previously had a baby with such a spine problem, or if someone in your family or your partner's family have had a baby with a spine problem your chances of this happening may be significantly higher. In this situation you should bring this to the attention of your doctor for further specific advice.
Genetic abnormalities, such as cystic fibrosis, can occur even without any family history in your or your partner's backgrounds. However, in some cases both you and your partner may be carrying an abnormal gene without it affecting either of you. If both of you happen to pass on that abnormal gene to your baby, then your baby may have as high as a one in four chance of having a serious disease.
A wide range of abnormalities affecting the development of a baby can be diagnosed prenatally. These include:
Chromosomal abnormalities (in which the baby has too many or too few chromosomes, such as Down syndrome)
Cardiac abnormalities (in which the chambers of the baby's heart, or the blood vessels connected to the heart, fail to develop normally, such as "hole in the heart")
Spine and head abnormalities (in which the bones of the spine or skull fail to develop normally, such as spina bifida)
Genetic conditions (in which the baby inherits abnormal genes from one or both parents, such as cystic fibrosis)
It is important to realize that prenatal tests cannot guarantee that your baby is going to be completely normal. This is because many medical conditions that affect children's health do not have suitable prenatal tests available yet, such as autism and cerebral palsy. You should discuss your particular concerns directly with Dr. Weiss to figure out if special additional tests might be suitable for your particular needs.