What is Premature birth?

Premature birth

What is premature birth?

Pregnancy normally lasts between 37 and 42 weeks. Having a baby before the 37th week of pregnancy is called a premature birth.

Sometimes doctors start labor early on purpose because the baby isn't growing well, or because the mother has a serious medical problem such as very

high blood pressure
Your blood pressure is considered to be high when it is above the accepted normal range. The usual limit for normal blood pressure is 140/90. If either the first (systolic) number is above 140 or the lower (diastolic) number is above 90, a person is considered to have high blood pressure. Doctors sometimes call high blood pressure "hypertension."

high blood pressure (a condition called preeclampsia). But most babies are born early because:

Source:
Morrison JJ, Rennie JM.
Clinical, scientific and ethical aspects of fetal and neonatal care at extremely preterm periods of gestation.
British Journal of Obstetric Gynaecology. 1997; 104: 1341-1350.

The mother goes in to labor before 37 weeks (called preterm labor)
The mother's water breaks before 37 weeks and before labor starts (called premature rupture of membranes).

It's hard to say who will have a premature birth.

A premature birth is when a baby is born before 37 weeks of pregnancy.

Most early births happen without any clear reason.

But we do know that women from poorer backgrounds have a higher risk of giving birth prematurely than other women.

Source:
Tucker J, McGuire W.
Epidemiology of preterm birth.
BMJ. 2004; 329: 675-678.

You're also more likely to have your baby early if:

You have given birth early before

Source:
Bloom SL, Yost NP, McIntire DD, et al
Recurrence of preterm birth in singleton and twin pregnancies.
Obstetrics and Gynecology. 2001; 98: 379�385.

³
You have had a

miscarriage
A miscarriage is when something happens during a pregnancy so that the fetus does not survive.

miscarriage late in pregnancy
You are carrying more than one baby (half of all sets of twins and most sets of triplets are born early)
You smoke

Source:
Kolas T, Nakling J, Salvesen KA.
Smoking during pregnancy increases the risk of preterm birth among parous women.
Acta Obstetricia et Gynecologica Scandinavica. 2000; 79: 644-648.

⁴
You have an infection in your birth canal or uterus

Source:
Steer P, Flint C.
Preterm labour and premature rupture of membranes.
BMJ. 1999; 318: 1059-1062.

⁵
Your

cervix
The cervix is a piece of tissue that sits between a woman's womb and her vagina. It has a small opening in it that gets much bigger when a woman is having a baby.

cervix is weak (called cervical incompetence) and tends to open (dilate) early
Your placenta bleeds (called antepartum hemorrhage)
You are African-American.

Source:
MacDorman MF, Minino AM, Strobino DM, et al.
Annual summary of vital statistics: 2001.
Pediatrics. 2002; 110: 1037-1052.

⁶

Sources for the information on this page:

Morrison JJ, Rennie JM.Clinical, scientific and ethical aspects of fetal and neonatal care at extremely preterm periods of gestation.British Journal of Obstetric Gynaecology. 1997; 104: 1341-1350.

Tucker J, McGuire W.Epidemiology of preterm birth.BMJ. 2004; 329: 675-678.

Bloom SL, Yost NP, McIntire DD, et alRecurrence of preterm birth in singleton and twin pregnancies.Obstetrics and Gynecology. 2001; 98: 379�385.

Kolas T, Nakling J, Salvesen KA.Smoking during pregnancy increases the risk of preterm birth among parous women.Acta Obstetricia et Gynecologica Scandinavica. 2000; 79: 644-648.

Steer P, Flint C.Preterm labour and premature rupture of membranes.BMJ. 1999; 318: 1059-1062.

MacDorman MF, Minino AM, Strobino DM, et al.Annual summary of vital statistics: 2001.Pediatrics. 2002; 110: 1037-1052.

This information was last updated on Nov 19, 2008

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment.
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