Table 3 Distribution of preterm births (PTB) for singleton pregnancies in the United States for the year 2013a
From: Spontaneous preterm birth and single nucleotide gene polymorphisms: a recent update
PTB Category | Gestation age (weeks) | Incidence in USA 2013 | Percentage of PTB |
|---|---|---|---|
Extremely preterm | <28 | 0.58 | 5.9 |
Severe or very preterm | 28–31 | 0.96 | 9.9 |
Moderately preterm | 32–33 | 1.18 | 12.2 |
Late preterm or near term | 34–36 | 6.99 | 72.0 |