Pregnancy Research Activities and Advances

Many programs within NICHD's Division of Population Health Research (DiPHR), Division of Extramural Research (DER), and Division of Intramural Research (DIR) conduct and support research on pregnancy. Researchers investigate a wide variety of topics related to improving the health of mothers and their fetuses, from before conception to the weeks and months after birth.

In 2014, NICHD launched the Human Placenta Project (HPP) to address gaps in our understanding of this vital organ and develop tools to study the structure and function of the placenta in real time. Ultimately, research stemming from this initiative could improve pregnancy outcomes and the health of the child and mother throughout life. Each year, NICHD hosts a meeting to bring researchers from the placenta field and other fields together to discuss recent advances in the HPP.

Details about studies in the areas of pre-pregnancy care and prenatal care, pregnancy complications, and labor and delivery follow below.

Pre-Pregnancy and Prenatal Periods

NICHD seeks to increase awareness about the importance of the pre-pregnancy and prenatal periods for promoting a healthy pregnancy and the best outcomes for mothers and babies. Areas of investigation include:

  • Investigating ways to improve the health of women and their children before, during, and after pregnancy. Studies supported by the Pregnancy and Perinatology Branch (PPB), within NICHD's DER, focus on the development of healthy babies; finding better ways to diagnose, treat, and prevent disease in pregnant women and newborns; increasing infant survival by reducing the number of preterm births and other birth complications; and evaluating the safety and effectiveness of devices and instruments for better care of mothers and their babies.
  • Evaluating techniques to develop and refine prenatal screenings. The DER's Intellectual and Developmental Disabilities Branch supports studies leading to the development and refinement of screening methods for conditions leading to intellectual and developmental disabilities.
  • Investigating the role of nutrition during pregnancy. Researchers supported by NICHD and the National Institute of Neurological Disorders and Stroke have reported new findings related to the interaction between folic acid supplementation, an important tool in prenatal care, and genetic pathways that could inform strategies to optimize the prevention of neural tube defects (NTDs) such as spina bifida (PMID: 20843827).

    In addition, researchers supported by the Pediatric Growth and Nutrition Branch of the DER are studying iron-deficiency anemia in newborns to determine if identifying and treating iron deficiency in pregnancy can reduce this prevalent problem.
  • Establishing a national standard for fetal growth. NICHD's DiPHR led a study called "The National Standard for Normal Fetal Growth" to find a standard of infant growth in both singleton and multiple pregnancies. Among the study's important findings to date, investigators characterized fetal growth in 1,737 low-risk pregnancies and found significantly different estimated fetal weights for white, Hispanic, Asian, and black infants at 39 weeks (PMID: 26410205). These ethnic differences in infant growth could lead to unnecessary tests and procedures in healthy pregnant women.
  • Studying medication use during pregnancy. The Effects of Aspirin in Gestation and Reproduction (EAGeR) Study, supported by the DiPHR, is examining the therapeutic value of low-dose aspirin in prenatal care. The research will analyze the effects of low-dose aspirin in combination with the intake of folic acid, compared with folic acid alone, on the incidence of miscarriage and other outcomes.

    The DER's Obstetric and Pediatric Pharmacology and Therapeutics Branch promotes research to improve the safety and effectiveness of medications for pregnant women. Some current studies include the study of clonidine to treat high blood pressure and metformin for the treatment of diabetes. In addition, a recent study on the effectiveness of Diclectin for nausea and vomiting found that the medication resulted in dramatically improved symptoms compared to placebo.
  • Evaluating effects of drinking alcohol and smoking tobacco on pregnancy outcomes. The Pregnancy and Perinatology Branch in the NICHD DER is studying alcohol use during pregnancy and its effects on infants. Other studies through the Prenatal Alcohol and SIDS and Stillbirth (PASS) Network are investigating the impact of alcohol use and tobacco smoking, both before and during pregnancy, on risk for Sudden Infant Death Syndrome (SIDS).

Pregnancy Complications

  • Preterm birth. NICHD served as the scientific lead for the Surgeon General's Conference on Preventing Preterm Birth in 2008, which developed the national agenda and action plan aimed at preventing preterm birth. This topic is an active research focus for NICHD. The following current or recently completed research efforts are supported by the PPB:

    • Evaluating whether treatments with antenatal steroids between 34 and 36 weeks of pregnancy will decrease infants' need for oxygen support. This trial found that treatment with antenatal steroids significantly reduced respiratory complications in singleton pregnancies at risk for late preterm birth (PMID: 26842679).
    • Studying women who are pregnant for the first time, with the goal of identifying factors in women who may be at risk for complications, including pregnancy-induced hypertension, preterm delivery, and low-birth-weight infants, during their first pregnancy.

    Researchers participating in the Maternal-Fetal Medicine Units Network, also supported by the PPB, found that use of progesterone by women at risk for preterm birth due to a prior preterm birth reduces the chances of a subsequent preterm birth by one third. 

    NICHD research formed the basis of a recent change to the gestational period within a pregnancy that is recognized as "full term." According to the new designations external link:

    • Early term is defined as 37 weeks through 38 weeks and 6 days.
    • Full term is defined as 39 weeks through 40 weeks and 6 days.
    • Late term is 41 weeks through 41 weeks and 6 days.
    • Postterm is 42 weeks and beyond.

    NICHD research documented poorer health outcomes, including a 20% greater risk of breathing, feeding, and temperature problems, among babies born at 37 and 38 weeks gestation compared to those born at 39 weeks or later. These findings contributed to the designation changes (PMID: 23645117). The findings and the designation changes are the focus of NICHD's Know Your Terms initiative.

    In addition, the Perinatal and Obstetrical Research Affinity Group within DIR studies aspects of preterm birth and other pregnancy complications with the aim of improving outcomes and reducing short- and long-term effects.

  • Gestational diabetes. The DiPHR Epidemiology Branch is currently studying the increased risk of hypertension in women with gestational diabetes mellitus. In addition, researchers in this Branch recently reported that women with gestational diabetes may be able to prevent the development of type 2 diabetes by following a healthy diet after pregnancy. Read more about this finding. More recently, these investigators found that following a healthy diet after a pregnancy with gestational diabetes also reduces the risk of high blood pressure.

    Another study, called the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) Follow-up Study, is supported by the PNGB. This study will explore whether elevated blood sugar during pregnancy influences later levels of body fat in children and development of diabetes in mothers following birth.

    In March 2013, NICHD sponsored the NIH Consensus Development Conference: Diagnosing Gestational Diabetes Mellitus. The expert panel recommended following the existing two-step process for diagnosing GDM as opposed to adopting a one-step process.
  • Preeclampsia. Studies are ongoing to determine whether abnormal levels of certain substances in the blood can predict preeclampsia. NICHD researchers and others have found that women who develop preeclampsia have higher levels of a substance called soluble fms-like tyrosine kinase 1 (sFlt1) and lower levels of placental growth factor and vascular endothelial growth factor than women who do not develop preeclampsia. Read more about preeclampsia research supported by NICHD.
  • Infections. Researchers investigating the expression and regulation of a group of innate immune receptors, called Toll-like receptors (TLRs), discovered that TLRs may play a role in infection-associated pregnancy complications by regulating the infection-induced inflammatory responses at the maternal-fetal interface.
  • Pregnancy loss (miscarriage and stillbirth). Another recent study supported by the PPB found that women experiencing two stressful life events in the year before their delivery were 40% more likely to have a stillbirth than were women who reported no such events. Investigators in the PPB's Stillbirth Collaborative Research Network also recently found that women who have a stillbirth delivery are at greater long-term risk for depression.

Labor and Delivery

  • The Consortium on Safe Labor, within the DIPHR Epidemiology Branch, evaluated the appropriateness of relying on the Friedman curve, which has traditionally been used to plot hours of labor against cervical dilation in centimeters, to guide decision making. This study found that labor progresses more slowly than previously believed. Researchers are tracking trends in preterm deliveries, practices such as induced labor, and how environmental and other factors may influence fertility, pregnancy, and pregnancy outcomes over time. Results from this study suggest that labor today may last longer than it did for women 50 years ago.
  • In addition, the Maternal and Pediatric Infectious Disease Branch supports research examining mother-to-child transmission of HIV and how this can be prevented during pregnancy and labor. Current research includes:
    • Studies on the epidemiology of HIV infection and complications in pregnant women and the safety of using new medications during pregnancy
  • Current studies in the Developmental Biology and Congenital Anomalies Branch of the DER include immunobiology of the placenta and maternal-fetal interactions. The Branch also funds opportunities for and studies on understanding embryonic development and the origin and development of structural congenital anomalies.
  • The Gynecologic Health and Disease Branch of the DER supports studies of interventions for identifying, preventing, and treating women at risk for obstetric fistula and other pelvic floor disorders. The National Center for Medical Rehabilitation Research funds the Center for Research on Women with Disabilities (CROWD), which completed the Final Report of the National Study of Women with Physical Disabilities in 1999. That report found that pregnant women with disabilities face significant challenges in finding health care providers who are knowledgeable about their disability to help them manage their pregnancy.

To achieve its goals for research on pregnancy and related disorders, NICHD supports a variety of programs, networks, and centers. A number of examples are included below.

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