Thanks to the work at the Perinatology Research Branch of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), led by Roberto Romero, MD, attention has consequently shifted toward prediction, identification of women at highest risk, and prevention of the onset of premature labor among those deemed to be at highest risk.
Cervical length in the mid-trimester is now a well-verified predictor of preterm birth, and vaginal progesterone has been shown to benefit women without other known risk factors who are diagnosed with a shortened cervical length.
We have consequently seen the preterm birth rate decline a bit. In 2013, the last year for which we have complete data, the preterm birth rate dropped to 11.4%, down from a high of 12.8% in 2006, according to the Centers for Disease Control and Prevention.
Infant mortality similarly remains unacceptably high, due largely to the high preterm birth rate and to our failure to significantly alter the prevalence of birth defects. In 2010, according to the CDC, the infant mortality rate in the U.S. was 6.1 deaths per 1,000 live births (compared with 6.87 in 2005), and the United States ranked 26th in infant mortality among countries belonging to the Organisation for Economic Co-operation and Development, despite the fact that we spend a significant portion of our gross domestic product (17.5% in 2014) on health care.
Birth defects have taken over as a leading cause of infant mortality after early newborn life, and while we’ve made some advancements in understanding and diagnosing them, the majority of causes of birth defects are still unknown.
On the maternal side of obstetrical care, our progress has similarly been more modest than we have hoped for. Preeclampsia remains a problem, for instance. Despite decades of research into its pathogenesis, our advancements have been only incremental, and the condition – particularly its severe form – continues to be a vexing and high-risk problem.
Added to such age-old foes, moreover, are the growing threats of maternal obesity and diabetes, two closely related and often chronic conditions that affect not only the health of the mother but the in-utero environment and the health of the fetus. Today, more than one-third of all adults in the U.S., and 34% of women aged 20-39 years, are obese, and almost 10% of the U.S. population has diabetes.
Both conditions are on the rise, and obstetrics is confronting an epidemic of “diabesity” that would not necessarily have been predicted 50 years ago. It is particularly alarming given our growing knowledge of how obesity can be programmed in-utero and essentially passed on from generation to generation, of how diabetes can negatively affect perinatal outcomes, and of how the two conditions can have an additive effect on fetal complications.
Achieving new moonshots
Concerted efforts in the past several decades to step back and try to understand the basic biology and physiology of term labor and of premature labor have better positioned our specialty to achieve the moonshot of significantly reducing the incidence of preterm birth.
Establishment in the mid-1980s of the NICHD’s Perinatology Research Branch was a major development in this regard, helping to build and direct research efforts, including basic laboratory science, toward questions about what triggers and propagates labor. There has been notable progress in the past decade, in particular, and our specialty is now on the right path toward development of therapeutic interventions for preventing prematurity.
Additionally, the NICHD’s recently launched Human Placenta Project is building upon the branch-sponsored animal and cell culture model systems of the placenta to allow researchers, for the first time, to monitor human placental health in real time. By more fully understanding the role of the placenta in health and disease, we will be able to better evaluate pregnancy risks and improve pregnancy outcomes.
We also are learning through research in the University of Maryland Birth Defects Research Laboratory, which I am privileged to direct, and at other facilities, that maternal hyperglycemia is a teratogen, creating insults that can trigger a series of developmental fetal defects. By studying the biomolecular mechanisms of hyperglycemia-induced birth defects and developing “molecular maps,” we expect to be able to develop strategies for preventing or mitigating the development of such anomalies. I hope and expect that these future advancements, combined with reductions in prematurity, will significantly impact the infant mortality rate.
Fetal therapy and surgery will also continue to advance, with a much more minimally invasive approach taken in the next 50 years to addressing the fetal condition without putting the mother at increased risk. Just as surgery in other fields has moved from open laparotomy to minimally invasive techniques, I believe we will develop endoscopic or laparoscopic means of correcting the various problems in-utero, such as the repair of neural tube defects and diaphragmatic hernias. It already appears likely that a fetoscopic approach to treating myelomeningocele can reduce maternal morbidity while achieving infant neurological outcomes that are at least as good as outcomes achieved with open fetal surgery.