![]()
Chapter 1
Overview of High-Risk Pregnancy
John T. Queenan1, Catherine Y. Spong2 and Charles J. Lockwood3
1Department of Obstetrics and Gynecology, Georgetown University School Medicine, Washington, DC, USA
2Bethesda, MD, USA
3Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, USA
With the changing demographics of the United States population, including increasing maternal age and weight during pregnancy, higher rates of pregnancies conceived by artificial reproductive technologies and increasing numbers of cesarean deliveries, complicated pregnancies have risen. Although most pregnancies are low risk with favorable outcomes, high-risk pregnancies – the subject of this book – may have potentially serious occurrences. We classify any pregnancy in which there is a maternal or fetal factor that may adversely affect the outcome as high risk. In these cases, the likelihood of a positive outcome is significantly reduced. In order to improve the outcome of a high-risk pregnancy, we must identify risk factors and attempt to mitigate problems in pregnancy and labor.
Many conditions lend themselves to identification and intervention before or early in the perinatal period. When diagnosed through an appropriate work-up before pregnancy, conditions such as rhesus (Rh) immunization, diabetes, and epilepsy can be managed to minimize the risks of mortality and morbidity to both mother and baby. It is not possible, however, to predict other conditions, such as multiple pregnancies, preeclampsia, and premature rupture of membranes prior to pregnancy. To detect and manage these challenging situations, the obstetrician must maintain constant vigilance once pregnancy is established.
Although much progress has been made since the 1950s, there is still much to accomplish. Fifty years ago, the delivering physician and the nursing staff were responsible for newborn care. The incidence of perinatal mortality and morbidity was high. Pediatricians and pediatric nurses began appearing in the newborn nursery in the 1950s, taking responsibility for the infant at the moment of birth. This decade of neonatal awareness ushered in advances that greatly improved neonatal outcome.
Many scientific breakthroughs directed toward evaluation of fetal health and disease occurred in the 1960s, which is considered the decade of fetal medicine. Early in that decade, the identification of patients with the risk factor of Rh immunization led to the prototype for the high-risk pregnancy clinic. Rh-negative patients were screened for antibodies, and if none were detected, these women were managed as normal or “low-risk” cases. Those who developed antibodies were enrolled in a high-risk pregnancy clinic, where they could be carefully followed by specialists with expertise in Rh immunization. With the advent of scientific advances such as amniotic fluid bilirubin analysis, intrauterine transfusion, and, finally, Rh immune prophylaxis, these often perilous high-risk pregnancies generally became success stories.
A note of caution is in order. The creation of special Rh clinics for Rh-immunized mothers in the early 1960s was a logical strategy since the Rh-immunized mother with an Rh-positive fetus had a 50% chance of losing her baby either in utero or in the nursery. With increasing technologic and scientific advances physicians achieved markedly better outcomes. We are sensitive to the use of the term “high-risk pregnancy” and believe it should be avoided in patient counseling as it can cause unnecessary anxiety for the parents.
During the 1970s, the decade of perinatal medicine, pediatricians and obstetricians combined forces to continue improving perinatal survival. Some of the most significant perinatal advances are listed in Box 1.1. Also included are the approximate dates of these milestones and (where appropriate) the names of investigators who are associated with the advances.
Box 1.1 Milestones in perinatology
Before 1950s
Neonatal care by obstetricians and nurses
1950s: Decade of Neonatal Awareness
| Pediatricians entered the nursery |
| 1950 | Allen and Diamond | Exchange transfusions |
| 1953 | du Vigneaud | Oxytocin synthesis |
| 1954 | Patz | Limitation of O2 to prevent toxicity |
| 1955 | Mann | Neonatal hypothermia |
| 1956 | Tjio and Levan | Demonstration of 46 human chromosomes |
| 1956 | Bevis | Amniocentesis for bilirubin in Rh immunization |
| 1958 | Donald | Obstetric use of ultrasound |
| 1958 | Hon | Electronic fetal heart rate evaluation |
| 1959 | Burns, Hodgman, and Cass | Gray baby syndrome |
1960s: Decade of Fetal Medicine
| Prototype of the high-risk pregnancy clinic |
| 1960 | Eisen and Hellman | Lumbar epidural anesthesia |
| 1962 | Saling | Fetal scalp blood sampling |
| 1963 | Liley | First intrauterine transfusion for Rh immunization |
| 1964 | Wallgren | Neonatal blood pressure |
| 1965 | Steele and Breg | Culture of amniotic fluid cells |
| 1965 | Mizrahi, Blanc, and Silverman | Necrotizing enterocolitis |
| 1966 | Parkman and Myer | Rubella immunization |
| 1967 | | Neonatal blood gases |
| 1967 | | Neonatal transport |
| 1967 | Jacobsen | Diagnosis of cytogenetic disorders in utero |
| 1968 | Dudrick | Hyperalimentation |
| 1968 | Nadler | Diagnosis of inborn errors of metabolism in utero |
| 1968 | Stern | NICU effectiveness |
| 1968 | Freda et al | Rh prophylaxis |
1970s: Decade of Perinatal Medicine
| Refinement of NICU |
| Regionalization of high-risk perinatal care |
| 1971 | Gluck | L:S ratio and respiratory distress syndrome |
| 1972 | Brock and Sutcliffe | α-Fetoprotein and neural tube defects |
| 1972 | Liggins and Howie | Betamethasone for induction of fetal lung maturity |
| 1972 | | Neonatal temperature control with radiant heat |
| 1972 | Quilligan | Fetal heart rate monitoring |
| 1972 | Dawes | Fetal breathing movements |
| 1972 | Ray and Freeman | Oxytocin challenge test |
| 1972 | ABOG | Maternal-Fetal Medicine Boards |
| 1973 | Sadovsky | Fetal movement |
| 1973 | | Real-time ultrasound |
| 1973 | Hobbins and Rodeck | Clinical fetoscopy |
| 1975 | ABP | Neonatology Boards |
| 1976 | Schifrin | Nonstress test |
| 1977 | March of Dimes | Towards Improving the Outcome of Pregnancy I |
| 1977 | Kaback | Heterozygote identification (Tay–Sachs disease) |
| 1978 | Bowman | Antepartum Rh prophylaxis |
| 1978 | Steptoe and Edwards* | In vitro fertilization |
| 1979 | Boehm | Maternal transport |
1980s: Decade of Progress
| Technologic progress |
| 1980 | Bartlett | ECMO |
| 1980 | Manning and Platt | Biophysical profile |
| 1981 | Fujiwara, Morley, and Jobe | Neonatal surfactant therapy |
| 1982 | Harrison and Golbus | Vesicoamniotic shunt for fetal hydronephrosis |
| Bang, Brock and Toll | First fetal transfusion under ultrasound guidance |
| 1983 | Kazy, Ward, and Brambati | Chorionic villus sampling |
| 1985 | Daffos, Hobbins | Cordocentesis |
| 1986 | | DNA analysis |
| 1986 | NICHD | MFMU network established |
| 1986 | Michaels et al | Cervical ultrasound and preterm delivery |
1990s: Decade of Managed Care
| Managed care alters practice patterns |
| 1991 | Lockwood et al | Fetal fibronectin and preterm delivery |
| 1993 | March of Dimes | Towards Improving the Outcome of Pregnancy II |
| Fetal therapy |
| Preimplantation genetics |
| Stem cell research |
| 1994 | NIH Consensus Conference | Antenatal corticosteroids |
2000s: Decade of Evidence-Based Perinatology
| 2000 | Mari | Middle cerebral artery monitoring for Rh disease |
| 2002 | CDC | Group B streptococcus guidelines |
| MFMU | Antibiotics for PPROM |
| 2003 | MFMU | Progesterone to prevent recurrent prematurity |
| 2006 | Merck | Immunization against human papillomavirus |
| 2008 | MFMU | Magnesium for prevention of cerebral palsy |
| 2009 | MFMU | Gestational diabetes trial |
2010s: Current Decade
| 2010 | NIH | Consensus conference on VBAC |
| 2011 | MOMS | Fetal surgery improves outcome for myelomeningocele |
ABOG, American Board of Obstetrics and Gynecology; ABP, American Board of Pediatrics; CDC, Centers for Disease Control; ECMO, extracorporeal membrane oxygenation; L:S, lecithin:sphingomyelin ratio; MFMU, Maternal-Fetal Medicine Units; MOMS, Management of Myelomeningocele Study: NICU, neonatal intensive care unit; NICHD, National Institute of Child Health and Human Development; NIH, National Institutes of Health; PPROM, preterm premature rupture of membranes; VBAC, vaginal birth after cesarean.
Among the advances in perinatal medicine that occurred during the 1980s were the development of comprehensive evaluation of fetal condition with the biophysical profile, the introduction of cordocentesis for diagnosis and therapy, the development of neonatal surfactant therapy, antenatal steroids and major advances in genetics and assisted reproduction. These technologic advances foreshadowed the “high-tech” developments of the 1990s. Clearly, the specialty has come to realize that “high tech” must be accompanied by “high touch” to ensure the emotional and developmental well-being of the baby and the parents. This decade was one of adjusting to the challenges of managed care under the control of “for profit” insurance companies.
The new millennium brought the decade of evidence-based perinatology. Clinicians became aware of the value of systematic reviews of the Cochrane Database. Major perinatal research projects by the Maternal-Fetal Medicine Units network of the Eunice Kennedy Shriver National Institute of Child Health and Human Development answered many clinical questions.
The future will bring better methods of determining fetal jeopardy and health. Continuous readout of fetal conditions will be possible during labor in high-risk pregnancies. Look for the new advances to be made in immunology and genetics. Immunization against group B streptococcus and eventually human immunodeficiency virus will become available. Preimplantation genetics will continue to provide new ways to prevent disease. Alas, prematurity and preeclampsia with their many multiple etiologies may be the last to be conquered.
New technology will increase the...
