The Role of the Maternal-Fetal Medicine Specialist (part 1)
Obstetrics is one area in medicine that has been greatly influenced by new technology and discoveries. Not only has there been an explosion of new information regarding normal physiology and pathology of pregnancy, but advances in medicine have also provided reproductive age women and men with a quality of life in which pregnancy may be considered. Better diagnosis and treatment, new medications and protocols, and more specialization in medicine have all been responsible for the new challenges seen in obstetrics today. The specialty of maternal-fetal medicine* was created to meet these challenges by providing expertise for women who may require special skills and resources. Maternal-fetal medicine specialists are trained obstetricians/gynecologists who have completed both a 4-year residency and a 3-year fellowship program leading to certification in various obstetrical, medical, and surgical complications of pregnancy. This highly trained group of physicians should provide an improvement in the outcome for the mother and the fetus, although there is little outcome data at the present time to support this concept. However, the maternal-fetal medicine specialist may provide an awareness or knowledge of recent approaches to the diagnosis and treatment of a particular condition so that management may be optimized.
This handout is directed at the non-medical person who is pregnant or considering pregnancy. Its purpose is to 1) help describe or understand risks associated with pregnancy, 2) describe the role or function of the high-risk or maternal-fetal medicine specialist, 3) provide some guidelines as to how a maternal-fetal medicine specialist may interact with other health care providers, and 4) list those acute and chronic medical and surgical conditions in which a maternal-fetal medicine specialist may enhance the outcome of pregnancy for both the mother and fetus.
The role of the MFM specialist can be diverse: as a consultant for the obstetrician, family practitioner, nurse midwives or as a direct provider of patient care. This specialized care may involve preconceptual counseling or advice, antenatal supervision or surveillance, and intrapartum or postpartum management. In some medical environments, the maternal-fetal medicine specialist may provide ultrasound evaluation of pregnancy. Although there is some data to suggest that all normal pregnant women may not need or require an ultrasound evaluation (1), the maternal-fetal medicine specialist is usually involved in pregnancy assessment for a specific indication. The accepted indications for an ultrasound evaluation during pregnancy are shown in Table 1 (2,3). The maternal-fetal medicine specialist is usually involved in a pregnancy assessment for a specific indication or when a routine ultrasound exam discovers an unsuspected abnormality.
The role of the maternal-fetal medicine specialist may also involve an interaction with internists or subspecialists in medicine and surgery. This may involve specific questions regarding medication use or the effects of pregnancy on a disease, or the disease on pregnancy. An example of this would be a patient with a long history of asthma, requiring various inhalers or medications. The asthma medications required for control are not different in pregnancy compared to non-pregnant patients. Well-controlled and treated asthma can lead to a normal pregnancy with little increased risk. However, asthma can complicate pregnancy by causing dehydration, infection, preterm labor, and intrauterine growth restriction. A successful outcome for this type of pregnant patient may often require the combined skills of an internist/pulmonologist with a maternal-fetal medicine specialist trained to evaluate these pregnancy complications.
There are several guidelines or approaches as to how a maternal-fetal medicine specialist may interact with colleagues. First, the maternal-fetal medicine specialist should be able to recognize and delineate the interaction between chronic medical conditions and pregnancy. A good and important example of this is illustrated by diabetes mellitus and pregnancy. The importance of glucose metabolism and the risk of congenital malformations is well-established (4,5). Euclycemic control in the preconceptual period; that is before pregnancy, may reduce the risk of congenital malformations to similar risk for a woman with normal glucose metabolism. Therefore, preconceptual counseling to achieve good glucose control is crucial, although many patients with diabetes mellitus do not receive this type of counseling. Furthermore, the risk of congenital malformations is even higher when the father of the pregnancy has diabetes. In a similar manner, the key factor for women with systemic lupus erythematosis appears to be the state of activity of the disease at the time of conception. Maternal and fetal outcome is optimal when the maternal condition is in remission for at least 6 months and with good renal function (6). Again, preconceptual counseling would be beneficial for this group of patients. Second, the effects of the pregnancy on the disease should be appreciated. For patients with diabetes mellitus, there is good data to support a general worsening of eye function during pregnancy, while renal function seems to be less affected or unaltered (7,8). Patients with congenital heart disease represent another good example of how pregnancy may influence a chronic condition. There is an extremely high (approximately 50%) maternal mortality associated with some cardiac conditions, i.e., pulmonary hypertension, and coarctation of the aorta with valvular involvement and Marfan's syndrome with aortic root dilation (9). Third, the specialist may be able to provide useful information regarding the use and choice of medications during pregnancy. For example, Aldomet has been the drug of choice for patients with chronic hypertension for many years. Algorithms have recently involved new agents. The angiotensin-converting enzymes or ACE inhibitors are examples of medications that should be avoided during pregnancy due to their association with a decrease in amniotic fluid, renal failure, and sudden intrauterine fetal demise (10). All medications can be classified into a specific category risk of pregnancy (11,12). These are categories, A, B, C, D, and X. In general, drugs classified in category A or B can be used in pregnancy with little risk. Category C is for drugs that should be given if the potential benefit justifies the potential risk to the fetus. Early studies may have revealed an adverse effect, but there are no controlled studies in human pregnancy. There may have been some studies in animals, or there are no available studies. With Category D drugs, there is positive evidence of fetal risk in human pregnancy, but the benefits for use in pregnancy may be acceptable even though there is a risk. Category X indicates that animal or human being studies have demonstrated a definite fetal risk, and these medications should be avoided in pregnancy. Examples of Category X drugs are folic acid, antagonists, and some medications known as teratogens, that are causing birth defects. Some well-known teratogens are listed in Table 2. And fourth, the recurrence risks of genetically inherited diseases can be discussed or investigated prior to conception. Often detailed karyotype and pedigree analysis can lead to a specific mode of inheritance or risk to the patient or family. Some examples of autosomal dominant inheritance are achrondroplasia, Huntington chorea, Marfan's syndrome, neurofibromatosis and polycystic kidney disease. Autosomal recessive inheritance is seen with cystic fibrosis, sickle cell anemia, Tay-Sachs disease and Thalassemias. X-linked inheritance is seen with Duchenne muscular dystrophy, hemophilia, and fragile-X syndrome. Recurrence risks can also be discussed with regard to risk associated with obstetrical complications of pregnancy, such as pregnancy-induced hypertension (preeclampsia) or placenta abruptio.
The acute and chronic medical and surgical conditions in which a maternal-fetal medicine specialist may enhance the outcome of pregnancy have been reported by the Society of Perinatal Obstetricians** in 1996 (13). The discipline of maternal-fetal medicine involves four major subgroups of patients. The first subgroup are patients undergoing diagnostic or therapeutic procedures. A common example in this group would be patients who are at risk for chromosomal abnormalities. In the United States, the risk of chromosomal abnormalities is considered increased when the mother is older than 35 at the time of expected delivery. The risk is also increased when the father is in his early or mid-fifties.