Premature births: U.S. rate rises while researchers struggle to understand why

Premature births: U.S. rate rises while researchers struggle to understand why

November is National Prematurity Awareness Month, launched by the March of Dimes in 2003. Sadly the U.S. has one of the highest preterm birth rate in the developed world — 1 of every 10 infants.

While preterm birth rates decreased 8.4 percent from 2007 to 2014 (in part because of declines in the number of births to young moms and teens), it rose in 2015 and 2016. The explanation? There is no definitive answer or research. We still do not fully understand why 40 percent of U.S. women who deliver early are first-time moms, or why 50 percent occur to women with no obvious risk factors. Research remains active and ongoing.

Recent studies show African-American women have a preterm birth rate about 50 percent higher than that of white women. Other studies conclude that preterm births can happen to any woman without warning — resulting in large health and financial societal challenges. Premature births cost 10 times as much as full-term births, and premature babies have 40 percent more doctor visits in the first year of life compared with babies born at term.

The traditional predictor of premature birth is a woman having had an earlier preterm baby. However, a prior premature birth history identifies only 6.1 percent of spontaneous premature births. Even when combined with the second traditional predictor of cervical length (identifying 11 percent of spontaneous premature births) — more than 80 percent of premature births are not identified before they happen.

Fortunately, today there is a blood test available, taken week 19 or 20 of pregnancy. It can tell moms-to-be of their risk for delivering prematurely. Called the PreTRM test, it is clinically validated to be a predictor of premature birth in women pregnant with one baby. Test results are delivered back to the women’s healthcare provider who then determines pregnancy management based on individualized risk assessment. If the results indicate high-risk, the doctor has the information needed to proactively monitor the pregnancy more closely — and mom-to-be is given the gift of time to prepare for a potential premature delivery. Alternatively, a low-risk result provides reassurance delivering early probably will not occur.

For certain, all pregnant women can initiate steps to improve their overall health and possibly reduce the risk of a preterm birth. They should not smoke, avoid alcohol and drugs, and receive early and consistent prenatal care throughout their pregnancies. Some research suggests progesterone treatments for reducing the risk of a preterm delivery when a pregnant woman has already had a preterm delivery. Other research suggests waiting 18 months or more between pregnancies to decrease the chance for preterm delivery.


A typical pregnancy is about 40 weeks long (from the first day of your last menstrual period to delivery) and divided into three sections called trimesters. Babies born after 39 weeks have the best health outcomes, compared with babies born before or after this period.

  • At 24 weeks of pregnancy a baby can survive outside of the womb, but to do so, round-the-clock care in the neonatal intensive care unit will be required. About the size of a small cantaloupe and weighing about 1.3 pounds, a baby born at 24 weeks has a 70 percent chance of survival and a life-long risk for developmental issues as well as intellectual and chronic medical disorders.
  • At 28 weeks of pregnancy, a baby can blink, but its eyes, brain, nervous system and lungs are still developing. The size of an eggplant and weighing about 2.25 pounds, babies born at 28 weeks are at high risk for respiratory distress syndrome (RDS), a breathing disorder that rarely occurs in full-term babies. These babies will need extra oxygen and help breathing until their lungs develop enough to breathe on own.
  • At 32 weeks of pregnancy a baby now has grown fingernails, toenails, and hair, but still needs to gain weight to help retain heat when born. The size of a pineapple and weighing around 3.75 pounds, a baby born at 32 weeks may face serious health issues, including RDS.
  • At 34 weeks of pregnancy, a baby is usually about 4.7 pounds and the size of a butternut squash. Still immature, the baby may have breathing problems and struggle with issues related to blood sugar, blood pressure, infection, and feeding.
  • At 36 weeks of pregnancy, a baby’s brain is still developing. If born now, the baby may have to go to neonatal intensive care for observation and special care. Slightly more than 5.75 pounds and the size of a romaine lettuce, the baby is at risk for developmental and academic delays.
  • At 38 weeks of pregnancy, most of a baby’s organs are developed but its lungs and brain continue to develop. Babies born at 38 weeks are about 7 pounds and may look as healthy as a full-term baby. However, he or she may have breathing problems, suffer from infections and require admission to neonatal intensive care.

In summary, preventing preterm birth — or prolonging gestation by just weeks — can reduce mortality and lifelong complications for babies as well as save billions of dollars. The best chance we have to do this is to identify women at risk and help them have the best pregnancy outcomes. Health-care professionals and researchers continue to look at marker combinations of preterm birth, focusing on protein levels in the blood, and social risk factors like age, nutrition, and socioeconomic factors.

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