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Pregnancy: Research Activities and Scientific Advances

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Institute Activities and Advances

Many programs within the NICHD's Division of Intramural 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. Details about studies in the areas of preconception care and prenatal care, pregnancy complications, and labor and delivery follow below.

Preconception Care and Prenatal Care

NICHD seeks to increase awareness about the importance of preconception care and prenatal care to promote a healthy pregnancy and the best outcomes for mothers and babies. Areas of investigation include:

  • Evaluating maternal health during pregnancy. Studies supported by the Pregnancy and Perinatology Branch (PPB), within the NICHD's DER, focus on the pathogenesis of symptomatic and asymptomatic maternal infections, the state of women's mental health during pregnancy, and the etiology and pathophysiology of sleep-disordered breathing in pregnancy.
  • 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 the 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. A current trial led by the NICHD's DIPHR focuses on establishing a standard for both singleton and multiple pregnancies. Researchers will measure fetal growth via ultrasound, working with 2,400 women from their first trimester through delivery.
  • 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 Dilectin for nausea and vomiting found that the medication resulted in dramatically improved symptoms compared to placebo (PMID: 20843504).
  • 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).

    In addition, an animal study by researchers in the Unit on Perinatal and Developmental Neurobiology, within the DIR, found that neuroprotective peptides may reduce changes in the immune system that are caused by prenatal exposure to alcohol. Fetal alcohol syndrome (FAS) and related disorders occur in children of mothers who consumed alcohol during pregnancy. These disorders often involve lifelong intellectual disability. Although many children with FAS or related conditions also have facial abnormalities, in other children the only sign of the disease is cognitive or behavioral impairment. Researchers aren't sure exactly how many children in the United States have FAS or related conditions, but estimates from the Centers for Disease Control and Prevention range from 2 to 15 cases for every 10,000 live births. Although fetal alcohol disorders can be prevented if women do not drink alcohol during pregnancy, treatments are needed to help reverse the effects of alcohol on the fetus and to help children who are born with the condition. To better understand exactly how alcohol can have such devastating effects on the fetus during early development, scientists treated pregnant mice with alcohol and then measured certain substances that show the body's immune response. The researchers found that some, but not all, of the immune system indicators were affected by alcohol. In a second experiment, scientists injected mice with a specific peptide that may reduce the changes in the immune system caused by alcohol, and then injected the mice with alcohol. They suspected that the mice treated first with the peptide would not show changes in the immune system, and that was exactly what happened. These results help scientists understand the effects of alcohol damage and may help them identify and test new interventions. (PMID: 23174390)
  • Assessing the effects of depression in pregnancy. Many women experience depression during pregnancy and in the early months after childbirth. Previous studies showed a link between docosahexanoic acid (DHA) and positive mental health. DHA is also known to be important for optimal brain development in the growing fetus and in infants. Based on these earlier findings, researchers conducted a study to examine whether symptoms of depression during pregnancy affect the concentration of DHA in breast milk. Researchers conducted a survey of 287 women to assess whether they experienced depressive symptoms. Four months after childbirth, breast milk samples were collected from the same women to measure the concentration of DHA. The results from the study showed that women who reported depressive symptoms in the first 20 weeks of pregnancy had lower concentrations of DHA in their breast milk. The same association was not found in women who reported depressive symptoms later in pregnancy. Because depression prior to pregnancy was not measured, it was unclear whether the women in this study were experiencing chronic depression or temporary depression due to stress or hormonal changes associated with pregnancy. However, because levels of DHA measured in breast milk are reflective of long-term influences on the body to store DHA over time, low levels of DHA in breast milk are likely associated with chronic depression. (PMID: 22223516)

Pregnancy Complications

  • Preterm birth. The 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 the NICHD. The following current 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
    • Investigating the mechanisms of disease responsible for preterm birth, including how certain maternal antibodies might induce labor
    • 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 “term” or “full term.” According to the new designations External Web Site Policy :
    • 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).
  • 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.

    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, the NICHD sponsored the NIH Consensus Development Conference: Diagnosing Gestational Diabetes Mellitus. The expert panel recommended following the current 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 the 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). Between 10% and 15% of pregnancies end in miscarriage. The risk of miscarriage is highest in the early weeks of pregnancy, when women may not know they are pregnant and a miscarriage could be mistaken for a late menstrual period. A study supported by the Population Dynamics Branch, in the DER, suggests that researchers need to consider awareness of pregnancy and knowledge about reproduction when analyzing data related to pregnancies and miscarriages. Since the 1970s, prenatal care has significantly improved and home pregnancy tests have become widely available. Home pregnancy tests allow women to quickly and easily confirm their pregnancy without having to see a doctor. While improved prenatal care could lower miscarriage rates, earlier detection of pregnancy could increase reported miscarriages. Scientists analyzed how reported miscarriage rates from 1970 to 2000 may have been affected by these changes. The researchers found that rates of reported miscarriages increased by about 1% per year. The greatest increase occurred in the first seven weeks of pregnancy, and there was no increase in reported miscarriages after 12 weeks of pregnancy. Additionally, although highly educated women are typically more likely to have access to prenatal care, women at higher education levels were more likely to report miscarriages. Taken together, these two findings suggested that the use of home pregnancy tests may have increased the awareness of otherwise unnoticed pregnancies, leading to more miscarriages being reported. The study also showed that although many health outcomes are worse for African American and Hispanic women, these groups had a lower risk of miscarriage than whites, especially during early pregnancy. These findings suggest possible differences in either knowledge of pregnancy-related symptoms or use of home pregnancy tests. (PMID: 22718315)

    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.

Labor and Delivery


Other Activities and Advances

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


Last Updated Date: 12/19/2013
Last Reviewed Date: 12/06/2013
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