By Rebecca Bowers

EXECUTIVE SUMMARY

In new research, investigators analyzed the risk of preterm birth among women with a previous poor pregnancy outcome. The results indicated that women had a higher chance of delivering before 32 weeks if their previous infant was born small for its gestational age. Those with a previous neonatal death were three times as likely to have a preterm birth subsequently, data indicated.

  • Babies who are preterm, defined as born before 37 weeks of gestation, have higher rates of death and disability.
  • The preterm birth rate (births at less than 37 weeks of gestation per 100 total births) in the United States rose from 9.57% to 9.85% during 2014-2016. According to the data, the rise in the total preterm birth rate reflects an increase in late preterm births (34-36 weeks), particularly in births that occur at 36 weeks.

Your next patient is a young mother who tells you her previous child was born preterm. What is your approach in talking with her about future pregnancies?

In new research, investigators analyzed the risk of preterm birth among women who had a previous poor pregnancy outcome. The results indicated that women had a higher chance of delivering before 32 weeks if their previous infant was born small for its gestational age. Those with a previous neonatal death were three times as likely to have a preterm birth subsequently, data indicated.1

Babies who are preterm, defined as born before 37 weeks of gestation, have higher rates of death and disability. Data from the Centers for Disease Control and Prevention (CDC) show that 17% of infant deaths in 2015 were attributed to preterm birth and low birth weight.2 Infants who are born too early may experience breathing problems, feeding difficulties, cerebral palsy, developmental delay, vision problems, and hearing problems.

Preterm births are on the rise in the United States. The preterm birth rate (births at less than 37 weeks of gestation per 100 total births) in the United States rose from 9.57% to 9.85% during 2014-2016. According to the data, the rise in the total preterm birth rate reflects an increase in late preterm births (34-36 weeks), particularly in births that occur at 36 weeks.3

Researchers Reviewed California Births

To conduct the analysis, researchers looked at women in California in their second pregnancy who reported a previous full-term birth, but encountered a problem with their first birth. Investigators looked at the type of adverse pregnancy outcome these women experienced, as well as the timing of preterm births.

Data indicate that women had an increased risk of preterm birth if they previously had an infant who was small for gestational age, experienced placental abruption, or had an infant die within the first 28 days of life. According to the analysis, the risk of giving birth before 32 weeks was higher for women who had an infant who was small for gestational age. Women with a previous neonatal death were three times as likely to experience a preterm birth subsequently.2

Prevent Premature Births

What are some other steps that women can take to prevent preterm birth? According to the Centers for Disease Control and Prevention (CDC), counseling on the following steps is recommended:

  • Discussing the importance of spacing the next pregnancy at least a year and a half from the woman’s most recent baby. Initiate the most effective contraceptive method the same day of the visit.
  • Stopping smoking. (To help women stop smoking, the CDC offers several resources, available at https://bit.ly/2J7hia0.)
  • Avoiding alcohol and drugs.
  • Receiving prenatal care as soon as the woman thinks she may be pregnant and throughout the pregnancy.
  • Seeking medical attention for any warning signs or symptoms of preterm labor. Warning signs of early labor include contractions every 10 minutes or less; a change in vaginal discharge; pressure in the pelvic area; a low, dull backache; cramps that feel like a menstrual period; and/or abdominal cramps that occur with or without diarrhea.
  • Discussing the use of progesterone treatment if the woman had a previous preterm birth.

Findings from a 2018 review suggest that consuming more omega-3 long-chain polyunsaturated fatty acids, found in fatty fish and fish oil supplements, reduces the risk of premature births. Data indicate that intake of such fatty acids decreases the risk of having a premature baby by 11%, reduces the risk of giving birth to an early premature baby by 42%, and drops the risk of having a small baby (defined as less than 2,500 grams) by 10%.4

Clinicians face challenges in attempting to predict delivery dates accurately for all types of pregnancies, especially in settings with limited resources. In pilot studies of pregnant women, data indicate that ribonucleic acid-based tests of maternal blood can predict delivery date and risk of early childbirth.5 If proven successful in advanced trials, such tests could aid in decreasing the preterm birth rate in the United States.

According to preliminary research, the new blood test, developed by a team of researchers at Stanford University, detects within 75-80% accuracy whether pregnancies will end in premature birth. The same technique also can be used to estimate the gestational age of a fetus as reliably as and less expensively than ultrasound, researchers concluded.5

REFERENCES

  1. Baer RJ, Berghella V, Muglia LJ, et al. Previous adverse outcome of term pregnancy and risk of preterm birth in subsequent pregnancy. Matern Child Health J 2018; doi: 10.1007/s10995-018-2658-z.
  2. Xu JQ, Murphy SL, Kochanek KD, et al. Mortality in the United States, 2015. NCHS data brief, no. 267. Hyattsville, MD: National Center for Health Statistics. 2016. Available at: https://bit.ly/2icuU9p. Accessed Jan. 17, 2019.
  3. Martin JA, Osterman MJK. Describing the increase in preterm births in the United States, 2014-2016. NCHS Data Brief, no. 312. Hyattsville, MD: National Center for Health Statistics. 2018.
  4. Middleton P, Gomersall JC, Gould JF, et al. Omega-3 fatty acid addition during pregnancy. Cochrane Database Syst Rev 2018;11:CD003402.
  5. Ngo TTM, Moufarrej MN, Rasmussen MH, et al. Noninvasive blood tests for fetal development predict gestational age and preterm delivery. Science 2018;360:1133-1136.