All about premature birth

About one-in-ten babies is now born prematurely and our scientific and medical understanding is increasing each day.

When is a baby considered premature?
A full-term pregnancy lasts for about 40 weeks from the first day of a woman's last menstrual period, but a delivery between 38 to 42 weeks is still considered full term.

When a baby is born at 37 weeks or before, the infant is considered premature and the birth preterm.

How do you calculate a premature baby's age?
A preemie's gestational age is the number of weeks completed in the womb at birth, as calculated from Mom's menstrual dates and the infant's maturational features at birth. The chronological age is the actual time since birth. Adjusted age is the chronological age corrected for the amount of prematurity. Adjusted age is commonly used when the subject is the baby's development, but chronological age is best for calculating the timing of healthcare visits and immunizations.

What are the causes of premature birth?
Known risk factors account for about only half of the cases of preterm delivery. These include infections like urinary tract infections, respiratory illnesses, and vaginal infections. That's why testing, using cultures, can be important. Treatment either before or during labor can prevent the spread of infection to the infant. Gum disease and undetected viral illnesses are also linked with increased rates of prematurity.

Multiple births
Twins, triplets, and beyond are seldom carried to term. Twins have a 25 to 50 percent chance of an early arrival, and the odds rise from there as the number of infants carried in the uterus increases.

Congenital irregularities
Ultrasound can help identify infants with irregularities in development that may prompt an early delivery. If the fetus needs an intervention before the due date, a premature delivery may be planned.

Mother's conditions
Moms with uterine or cervical abnormalities; chronic illnesses such as kidney disease, preeclampsia/eclampsia (a pregnancy-related illness with high blood pressure), or diabetes; or a poorly functioning, bleeding, or damaged placenta usually require early delivery of the baby. Delivery may be by Cesarean section (C-section) or induced for the well-being of the mother and/or the baby.

Other factors have been linked to a higher rate of preterm birth. These involve:

  • women who have had a previous preterm delivery
  • women who become pregnant six weeks or less after a previous birth;
  • women who are underweight at conception or who gain less than 20 pounds during pregnancy;
  • very young mothers and women over 40;
  • women who work on their feet late into pregnancy or perform heavy labor or are subject to a lot of physical or emotional stress;

Myths about preterm birth
Most preterm moms and dads wonder what they did to cause an early delivery and feel some guilt. In the vast majority of cases, there is nothing that could have been done to prevent an early birth. But myths continue and include:

  • sex in the third trimester
  • worrying
  • bad thoughts
  • arguments with your partner
  • air travel
  • bad food
  • swimming

About 20 percent of preterm infants are delivered electively (have a planned delivery) because of the mother's or infant's condition and to avoid the stress of labor; some births have labor induced. Another 30 percent have a preterm delivery after the membranes rupture, and about half of all preterm births are delivered after the start of preterm labor.

Labor is started or a caesarian delivery proposed if the infant is in distress, termed fetal distress.

If Mom has a high-risk condition and/or a very preterm delivery is imminent, she may be transferred to a high-risk center for delivery. This will allow her needs and those of her infant, who will require very specialized care, to be met.

Preventing prematurity
Preventing all preterm births is not possible, but good prenatal care and good medical care between pregnancies can help lower the numbers.

Women with a high-risk condition or with any chronic or acute health condition should see their health care provider early and often. Good nutrition, appropriate weight gain, and no smoking or drug use also will reduce the preterm rate, as will better diagnosis of subtle infections.

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