What is a premature birth?

Babies born later than the thirty-seventh week of pregnancy and
before the forty-second week are known as term or full-term infants, and birth
anywhere during this period is within the window of normal gestation. By
definition, babies born at or before the thirty-seventh week are called preterm or
premature infants. (Babies born beyond the forty-second week are post-term
infants.)

Every pregnancy and birth carry risk to both infant and mother. Preterm and
premature infants, however, are at high risk. They have both a lower survival rate
and more medical complications with potential lifelong effects than full-term
babies. In 2012, one of every nine babies in the United States was born
prematurely, accounting for more than 450,000 preterm infants, according to the US
Centers for Disease Control and Prevention. Preterm infants make up the majority
of the low-weight
births that occur annually and a large proportion of infant
deaths.

Developmental prematurity and survivability. Prior to twenty-four
weeks of gestation, fetuses are not considered to have developed sufficiently to
live outside the womb. Somewhere between twenty-four and twenty-eight weeks of
gestation, however, the fetus does become viable, although any baby born between
twenty-four and thirty weeks is called very premature. The lengths of these
infants range from eleven to eighteen inches, and weights can range from one
pound, five ounces to almost four pounds. At this stage of development, a few
ounces more or less make a big difference in the baby’s ability to survive.
Neonates at two pounds have little better than a one in two chance of survival;
infants at 3.5 pounds have better than a nine in ten chance.

Babies born between thirty-one and thirty-six weeks of gestation are considered
moderately premature. These babies do well, with a 90 to 98 percent survival rate,
and weigh from a little more than three to almost four and one-half pounds.
Typical lengths range from sixteen to nineteen inches.

Parents who expect their very premature baby at five to nine weeks of age to
resemble a moderately premature baby born at thirty-five weeks will be
disappointed. The very premature still appear much less like babies, are
significantly lighter, and remain behind developmentally. They are often unready
to be bottle-fed or breast-fed or to sleep in an open crib, and they are generally
less alert and have less behavioral control than the moderately premature. Simply
reaching the same number of chronological weeks as moderately premature babies
does not negate the substantial differences in their developmental beginnings.

Borderline premature infants are born during weeks thirty-seven or thirty-eight
are much like full-term newborns: They have almost the identical survival rate (98
percent) and approach average weights. Nevertheless, they are still at greater
risk for respiratory distress syndromes, neonatal
jaundice, unstable body temperatures, and a variety of
problems associated with feeding.

The causes of prematurity and preterm births. Although many
conditions result in premature birth, not all causes are known. Some well-known
causes include toxemia in the mother (a multistage disease that begins with
high blood pressure and rapid fluid retention and may progress to brain
hemorrhage, seizure, and coma), placenta previa (when the placenta
implants in the lower uterus), placenta abruptio (when a normally positioned
placenta detaches from the uterus), premature membrane rupture (when the tissue
containing the amniotic fluid tears or leaks before labor begins), incompetent
cervix (when the cervix opens mid-pregnancy), and multiple births (twins,
triplets, and so on). Cigarette smoking, alcohol use, or drug use during pregnancy
also increase the risk of premature birth. High blood pressure, diabetes mellitus,
sickle cell disease, and kidney disease are other risk factors for premature
birth.

Some mothers blame themselves for the premature births of their infants. While it
is natural to look for a cause and a target to vent the often-powerful feelings
associated with prematurity, it is the rare mother who deliberately causes her
baby to be born earlier than necessary. In fact, some causes do not involve the
mothers at all, including congenital defects in the infant, intrauterine
illnesses, and defective placentas.

The vast majority of women will never deliver prematurely. Those who do, however,
run about a 30 percent chance of having a second premature birth, according to the
March of Dimes. In the rush to understand and find answers to prematurity, it is
important not to overinvest in probability statistics and comparative risk factor
data, which include race, paternity, and even a woman’s own mother’s exposure to
biochemicals. It is extremely important to realize that many women who are
formally classified as high-risk mothers have normal deliveries of full-term
babies, and that others, who are healthy and without known risk factors, deliver
premature, preterm babies.

In 2003, scientists announced an exciting discovery in the search for preventing
premature labor and birth. More than three hundred high-risk pregnant women—those
who had given birth prematurely before—were given weekly injections of the hormone
progesterone. This therapy reduced the chance of preterm birth by 34 percent, a
number that elated the study’s researchers. The use of progesterone therapy has
been especially effective in the cases of women with short cervixes. Another study
in 2002 suggested that measures used to detect early labor—including a medical
device worn on the abdomen to record contractions, ultrasound examinations of the
cervix, and a test for a chemical called fetal fibronectin—seem not to work very
well in preventing preterm birth, leading researchers to continue to seek ways to
predict and prevent premature delivery. Early detection of labor is important
because it can allow doctors to prescribe antibiotics, medication to slow the
contractions or help the fetus develop more quickly, or bed rest.

Warning signs of premature labor include a contraction every ten minutes within
one hour before thirty-seven weeks of pregnancy, menstrual-like cramps, pelvic
pressure, and an increase in vaginal discharge. If a pregnant woman suspects she
is going into labor prematurely, she should call her health care provider
immediately and continue to monitor her symptoms. Sometimes, lying down and
hydrating can cause preterm contractions to abate; however, if the symptoms of
premature labor continue, the pregnant woman should seek immediate medical
attention. Magnesium sulfate may given to slow preterm contractions, and
corticosteroids may be administered to accelerate the baby's lung and brain
development prior to preterm delivery.

The psychological impact. There may be no event with a greater
impact on a person’s life than becoming a parent, and few events in a parent’s
life equal the impact of seeing one’s tiny, struggling, and high-risk baby. It is
common for parents to have been forewarned of the baby’s chances, especially if
the infant is very premature. They may, in fact, have begun to prepare themselves
psychologically for the death of their baby even as the baby clings to life
outside the womb. They may try to protect themselves from bonding to one whose
death may be imminent.

Their distress, confusion, and contradictory feelings can overwhelm them. Their
babies may not look much like the babies they had pictured or prepared for, and
they may not feel much like parents. Premature birth can be a crisis rarely
equaled in a parent’s life.

Some couples react and adapt successfully, while others do not. Nearly all parents
of premature infants experience various forms of shock, denial, anger, guilt, and
depression. Researchers who study and compare parents who cope better and worse
have learned that those parents who accept and express their whole range of
emotions (versus only the emotions that they believe they are supposed to have),
who seek further information, who accept help in their caring for the babies, and
who begin to develop an early relationship with their babies adapt to the crisis
well and successfully.

Premature infants were thought, at one time, to be inactive, unaware, and inert.
Research and anecdotal observation strongly support the view that these infants
are acutely sensitive to their environment, though they usually respond in ways
too subtle to be perceived casually. When parents are present, even on the outside
of the incubator wall,
their babies behave differently, tolerate feedings better, and heal more quickly
and completely.

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