A premature infant is an infant born before 37 weeks' gestation. Prematurity is common, with an occurrence of 11% of live births in the US.
In addition to immediate post-birth resuscitation, efforts to reduce excessive oxygen exposure, hyperventilation, hypothermia, and hypoglycemia must be made. Consultation with a neonatologist as soon as possible is recommended to provide expertise to reduce potential morbidity.
Gestational age determination done within hours of birth is important for designating further care of the premature newborn. The risk of adverse outcomes varies inversely with gestational age.
The New Ballard Score uses measurements of neuromuscular and physical maturity to complement the maternal history and ultrasonographic findings to estimate gestational age, although a first-trimester ultrasound remains the most accurate assessment of gestational age.
Extremely premature infants (gestational age <28 weeks) exhibit the greatest morbidity and mortality, although complications may occur with any degree of prematurity.
A premature infant is an infant born before 37 completed weeks of gestation. Term infants are defined as those born between 37 and 41 weeks of gestation.
History and exam
- maternal last menstrual period (LMP)
- distance from the maternal superior pubis to the uterine fundus
- infant physical maturity score
- infant neuromuscular maturity score
- combined physical/neuromuscular score <10: gestational age <28 weeks
- combined physical/neuromuscular score 11 to 19: gestational age 29 to 31 weeks
- combined physical/neuromuscular score 20 to 24: gestational age 32 to 33 weeks
- combined physical/neuromuscular score 25 to 33: gestational age 34 to 36 weeks
- intrauterine infection
- preterm premature rupture of membranes (PPROM)
- pre-eclampsia/pregnancy-induced hypertension
- placental abruption/antepartum hemorrhage
- abnormal amniotic fluid volume
- severe bacterial vaginosis
- multiple gestation
- previous preterm birth
- fetal abnormality
- cervical incompetence/uterine abnormality
- gestational diabetes
- maternal surgery during pregnancy
- chronic maternal illness
- short interpregnancy time interval
- drug use (tobacco, cocaine, heroin)
- maternal pregnancy body mass index <19 or >35
- nonwhite race
Mohan Pammi, MD, PhD
Section of Neonatology and Department of Pediatrics
Baylor College of Medicine
MP declares that he has no competing interests.
Dr Mohan Pammi would like to gratefully acknowledge Dr Stephen Welty and Dr James L. Wynn, previous contributors to this topic.
SW and JLW declare that they have no competing interests.
Isaac Babarinsa, MSc, MRCOG
Consultant Obstetrician and Gynaecologist
Gloucestershire Royal Hospital
IB declares that he has no competing interests.
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