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What do Maternal-Fetal Medicine Subspecialists do?

Maternal-fetal medicine (MFM) subspecialists treat two patients at the same time. We partner with the mom-to-be, her family, and her medical team to navigate the un-routine and achieve the best possible outcome. We see families who have experienced high-risk pregnancies in the past, women with chronic health conditions, and women who develop unexpected problems during their pregnancy.

Preconception care

Before pregnancy, MFMs can provide advice for women with chronic health conditions or those who have experienced a high-risk pregnancy in the past. At a preconception consultation, the MFM reviews a woman’s medical and pregnancy history and helps to map out an optimal strategy for her next pregnancy.

Genetic screening, ultrasound, and prenatal diagnosis

MFMs use ultrasound, blood tests, and procedures such as amniocentesis to look inside the womb and evaluate the developing fetus. We use advanced skills in 3D and 4D ultrasound and fetal echocardiogram to screen for birth defects and chromosome problems. We also work closely with genetic counselors to offer tests such as integrated screening, noninvasive prenatal testing, chorionic villous sampling, and amniocentesis.

  • Diagnostic amniocentesis: Guided by ultrasound, the MFM uses a needle to collect a small amount of amniotic fluid. We use this fluid to test for genetic diseases, fetal lung maturity, or infection.
  • Therapeutic amniocentesis: When a fetus has too much amniotic fluid, the MFM can place a needle in the uterus, guided by ultrasound, and remove extra fluid. This process can reduce the risk of early birth and treat certain fetal diseases
  • Chorionic villus sampling (CVS): In a CVS, the MFM uses a thin tube or a needle to sample the placenta during the first third of the pregnancy. The MFM uses ultrasound to perform a CVS, either through the cervix or the abdomen. We can test the placental sample for certain fetal diseases and health conditions.

Labor and delivery

MFMs work with other OB care providers to ensure high-quality care during labor and childbirth. We provide expert advice on when to induce labor, when and how to monitor the fetal heart rate, and whether a cesarean delivery is indicated. Our training provides us with advanced skills for attending complicated births, such as vacuum or forceps-assisted births, cesarean birth, or trial of labor after cesarean.

Pregnancy problems

Women who have experienced a high-risk pregnancy in the past face higher risks with their next pregnancy. In other cases, unexpected problems arise during pregnancy. We help manage problems such as the following:

Recurrent pregnancy loss

Women who experience multiple miscarriages may have an underlying health problem that makes it more difficult for them to carry a pregnancy. MFMs can assess for such problems and recommend treatments to reduce risk in the next pregnancy.

Preterm birth

      • Early contractions (preterm labor) or water breaking (preterm premature rupture of membranes, or PPROM): For some women, the normal events of labor start too early, putting the fetus at risk of being born before he or she is ready for the outside world. MFMs give drugs to slow preterm labor and steroid injections that jump-start the baby’s biology, preparing the baby for the outside world if born early.
      • Shortened cervix: The cervix keeps the uterus closed until it is time for birth. However, some women experience cervical insufficiency, a painless thinning of the cervix that can lead to preterm birth. MFMs work with women and their OB care providers to treat early thinning cervix with medications or surgery to prevent early birth.
      • Cerclage: In some cases, surgery can strengthen a thinning cervix. In this procedure, the surgeon sews the cervix shut, either through the vagina or through an incision in the abdomen, to prevent pregnancy loss. Some surgeons perform this procedure with minimally invasive surgical techniques, including robotic-assisted cerclage.
      • Preterm birth in a prior pregnancy: Multiple factors can impact a mother’s risk of giving birth too soon. MFMs can identify problems, such as an abnormally shaped uterus, that can contribute to preterm birth. Based on this evaluation, they recommend therapies to prevent preterm birth in the next pregnancy.

Blood pressure problems

In healthy pregnancies, hormones lower a woman’s blood pressure and direct food and oxygen to the womb. Sometimes, however, signals from the placenta increase a woman’s blood pressure, leading to problems such as gestational hypertension, preeclampsia, HELLP syndrome, and eclampsia. The cure for these conditions is to deliver the baby, which is risky when high blood pressure develops months before a baby’s due date. In these situations, MFMs assess the pros and cons of staying pregnant vs. giving birth to improve outcomes for mother and baby. For women who have previously had blood pressure problems during pregnancy, MFMs can map out a strategy to minimize risk for their next birth.


During pregnancy, the placenta delivers vital nutrients and removes waste products from the growing baby. Shortly after birth, a healthy placenta detaches from the uterus and passes out of the mother’s body. If the placenta is located over the cervix, or if it begins to detach before the baby is born, women may experience bleeding.

      • Placenta previa: Usually, the placenta attaches to the uterus far from the cervix. In cases of placenta previa, the placenta blocks the birth canal. If the mother labors while the placenta is blocking the cervix, she can experience heavy bleeding. MFMs monitor women with placenta previa and help determine a safe time for birth.
      • Placenta accreta, increta, and percreta: In these conditions, the placenta is attached too tightly to the wall of the uterus, and it cannot separate after the baby is born. This problem is more common after previous surgeries on the uterus, such a cesarean delivery, that scar the uterine wall, particularly if there is a placenta previa. Women with placenta accreta typically require a hysterectomy (removal of the uterus) at the time of birth to control life-threatening bleeding. MFMs can use ultrasound to estimate the risk of accreta, and they work with expert surgeons to plan a safe birth for mother and baby.
      • Partial placental abruption: If a woman experiences bleeding during pregnancy and an ultrasound shows that the placenta is not too close to the cervix (placenta previa), then she may be diagnosed with a partial abruption. In a partial abruption, a small amount of the placenta detaches from the wall of the uterus, causing bleeding.
      • Complete abruption: In a complete abruption, most or all of the placenta detaches from the uterus before the baby is born. Women with complete abruption need urgent surgery to delivery the baby and control bleeding.

Maternal health problems

Pregnancy can worsen existing health problems, such as high blood pressure, diabetes, or kidney disease, and these chronic conditions can affect pregnancy. MFMs monitor these high-risk pregnancies and offer expert guidance on what medications can manage mom’s medical problems with minimal risk to the baby. The following sections list some of the preexisting health conditions that may complicate a woman’s pregnancy and for which the expert care of an MFM may be needed.   


During pregnancy, a woman’s heart is beating for two. The amount of blood the heart pumps increases by almost 50% by the end of pregnancy, creating challenges for women with heart conditions.

      • Congenital heart disease
      • Arrhythmias
      • Valve disease
      • Cardiomyopathy
      • Pulmonary hypertension
      • Coronary artery disease
      • Heart transplant


Women breathe more deeply during pregnancy, taking in more oxygen and breathing out extra carbon dioxide. Women with chronic lung problems may struggle with this added burden.

      • Asthma
      • Pneumonia
      • Restrictive lung disease
      • Influenza
      • Tuberculosis
      • Cystic fibrosis


Having extra body fat increases a pregnant woman’s risk of diabetes, high blood pressure, birth defects, and cesarean delivery. Mothers who enter pregnancy overweight or obese can benefit from expert advice on nutrition, advanced ultrasound, and expert management during labor.

Endocrine Glands

Pregnancy hormones change how a woman’s body responds to stress, regulates blood sugar, and controls the flow of nutrients such as calcium and vitamin D. Women with endocrine conditions need expert advice to adjust to the demands of pregnancy and to return to normal after childbirth.

      • Addison's disease
      • Diabetes, insulin-requiring/dependent
      • Thyroid disease
      • Parathyroid disease
      • Pheochromocytoma


During pregnancy, a woman’s digestive system slows so that her body can absorb the nutrients she needs to grow a baby. These changes likely contribute to morning sickness, and they can worsen existing conditions such as gallstones and heartburn.

      • Nausea and vomiting of pregnancy; hyperemesis gravidarum
      • Eating disorders
      • Intrahepatic cholestasis
      • Inflammatory bowel disease (ulcerative colitis; Crohn's disease)
      • Gallbladder disease (cholecystitis; cholelithiasis)
      • Pregnancy after liver transplantation
      • Pancreatitis
      • Wilson’s disease


A woman’s blood volume rises almost 50% during pregnancy. Blood clots form more easily, most likely as a way of preventing heavy bleeding during childbirth. For women with low blood counts or clotting problems, these changes can require special care to keep mother and baby healthy.

      • Maternal anemia and hemoglobinopathies
      • Sickle cell disease
      • Von Willebrand disease
      • Thrombotic thrombocytopenia purpura/hemolytic uremic syndrome
  • Venous thromboembolism and anticoagulation
  • Inherited thrombophilia


The kidneys work overtime during pregnancy to filter out both mom’s and baby’s waste products. Women with kidney disease may require special blood pressure monitoring during pregnancy to protect their kidneys while meeting the baby’s needs.

  • Kidney transplant
  • Nephropathy
  • Chronic renal insufficiency


Hormonal changes and greater blood volume can aggravate or improve neurologic problems. The stresses and hormonal changes of pregnancy can also complicate psychiatric conditions. Some medications to treat these conditions may also affect the baby’s health. For both neurologic and psychiatric diseases, it is essential to plan ahead and choose treatments that keep a woman healthy while minimizing risk to the growing fetus.

Neurological conditions:

  • Seizure disorders
  • Headache
  • AV malformation/Berry aneurysm
  • Multiple sclerosis
  • Pseudotumor cerebri
  • Myasthenia gravis
  • Spinal cord injury
      • Diabetes insipidus

Psychiatric conditions:

  • Drugs of abuse
  • Depression
  • Other psychiatric disorders
  • Domestic abuse

Immune System and Infection

Pregnancy changes a woman’s immune system, adjusting her biology so that it does not reject the growing baby. These changes can increase her risk of some infections. Other infections can cause birth defects and may require specialized treatment during pregnancy. Changes to the immune system may also affect autoimmune disorders.

Infectious disorders:

  • Hepatitis A
  • Hepatitis B
  • Hepatitis C
  • HIV
  • Gonorrhea
  • Chlamydia
  • Syphilis
  • Trichomonas
  • Group B streptococcus
  • Rare infections
  •  Vaccination

Autoimmune disorders:

  • Antiphospholipid syndrome
  • Systemic lupus erythematosus

Surgical Emergencies

When surgical emergencies occur in pregnancy, MFMs partner with surgeons to ensure the health of two patients at the same time.

  • Trauma
  • Critical care
  • Nonobstetric abdominal surgery in the current pregnancy

Bone, Cartilage, and Skin

Pregnancy stretches joints and tissues, affecting women disorders of their bones, cartilage, and connective tissue.

  • Marfan syndrome
  • Maternal skeletal dysplasia
  • Dermatoses


For cancer survivors, pregnancy may stress organs that were strained by chemotherapy, requiring extra monitoring. In other cases, mothers receive a cancer diagnosis while pregnant. MFMs partner with medical and surgical oncologists to map out surgery, chemotherapy, and timing of birth to minimize risk to mother and child.

Birth Defects

Improvements in ultrasound, prenatal diagnosis, and treatment have made it possible to detect and, in some cases, treat, many birth defects before birth. MFMs provide expert consultation for families who have learned of a birth defect, working with pediatric surgeons to determine the best plan of care for mother and fetus.

  • Central nervous system
  • Spinal cord (spina bifida)
  • Chest
  • Heart
    • Structural
    • Arrhythmias
  • Gastrointestinal
  • Genital
  • Kidney and bladder problems
  • Skeletal dysplasias
  • Umbilical cord
  • Chromosome problems, such as Down Syndrome (Trisomy 21), Trisomy 13 and Trisomy 18
  • Genetic syndromes
  • Exposure to drugs and chemicals

Fetal complications

Twins, triplets and more

Carrying two or more babies increases the risk for early labor and problems with growth, as the mother’s uterus stretches to accommodate multiples. When two babies share a single placenta, there are added challenges, because uneven blood flow can lead to problems such as twin-twin transfusion syndrome. MFMs monitor multiple pregnancies with ultrasound, and they can perform advanced procedures to treat complications such as twin-to-twin transfusion syndrome.

Growth problems

  • Fetal growth restriction (FGR): Problems with blood flow to the placenta can slow a baby’s growth. In other cases, infections, chromosomal problems, or genetic disorders keep the baby from growing as expected. MFMs use advanced ultrasound techniques and tests such as amniocentesis to determine the cause of slow growth, monitor blood flow to the baby, and determine the right time for birth.
  • Macrosomia: In other cases, babies grow too fast. High blood sugar due to diabetes in pregnancy can speed up growth, as can certain genetic problems.


The fetal immune system is not ready to cope with certain infections, which can cause birth defects or growth problems. Advanced treatment and careful monitoring may reduce long-term effects of infections such as cytomegalovirus, toxoplasmosis, parvovirus, herpes, and varicella (chickenpox).

Fetal death

For families who lose their babies before birth, MFMs can help to determine what caused the loss and develop a plan to reduce risk in the next pregnancy.


Some mothers develop antibodies, such as anti-D and Kell, that can cross the placenta and attack fetal red blood cells. MFMs can test whether the fetus is at risk, use ultrasound to monitor for signs of anemia, and give intrauterine blood transfusions to support affected fetuses.

Other conditions

  • Neonatal alloimmune thrombocytopenia (NAIT): NAIT develops when a mother has antibodies that attack fetal platelets, leading to risks of bleeding before birth.
  • Nonimmune hydrops: A fetus with nonimmune hydrops develops swelling and excessive fluid in the heart, lungs, and abdomen. Multiple problems, ranging from birth defects to genetic disorders, can lead to nonimmune hydrops. MFMs sort out possible causes and try to treat the underlying problem.

Fetal testing

MFMs perform a variety of tests to check the effectiveness of certain treatments as well as monitor fetal well-being.

Antepartum fetal monitoring

We use 2D ultrasound to monitor fetal heart rate, fetal movement, and levels of amniotic fluid, and we use Doppler ultrasound to measure blood flow through the umbilical cord and the fetal brain and heart. These tests help sort out whether the fetus is getting what it needs in the uterus, or might be better off being born.

Ultrasound assessment of amniotic fluid

Healthy babies have enough fluid around them, but not too much. Using ultrasound, we can estimate whether a baby has too little fluid (oligohydramnios) or too much (polyhydramnios). Both too much and too little fluid can be associated with birth defects and placental problems.

Fetal blood sampling and transfusion

Guided by ultrasound, an MFM can insert a needle into the umbilical cord to collect a fetal blood sample to diagnosis certain diseases. We can also give the fetus a blood transfusion to treat severe anemia.

Advanced fetal treatment

In specialized centers, MFMs partner with pediatric surgeons to repair life-threatening birth defects before birth. Some procedures are performed endoscopically, through tiny incisions using cameras, such as for twin pregnancy or other fetal anomalies. In other conditions, the MFM opens the uterus to perform fetal surgery for birth defects such as spina bifida.

Postpartum care

MFMs provide care after birth for women who experience complications such as heavy bleeding, bloodstream infections, surgical complications, or seizures. We partner with intensive care specialists to care for the sickest new mothers.

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