gsBP | P value* | |||

Low (<25th percentile), n=1395 | Intermediate (25th–75th percentile), n=2790 | High (>75th percentile), n=1395 | ||

Gestational age (weeks) | 28.0±2.2 | 28.2±2.2 | 28.2±2.2 | 0.02 |

Birth weight (g) | 1021±291 | 1023±303 | 1023±299 | 0.86 |

Girls (%) | 46.7 | 47.8 | 47.2 | 0.85 |

Multiple birth (%) | 28.7 | 27.1 | 28.9 | 0.93 |

Small for gestational age (%) | 11.1 | 12.8 | 12.7 | 0.22 |

Lowest mean blood pressure on the first day of life (mm Hg) | 27.3±6.2 | 27.6±6.4 | 27.9±6.4 | 0.009 |

*Two-sided p value comparing groups with low vs high gsBP. Gestational age, birth weight and mean blood pressure are given as mean±SD and compared with t-test. Fisher’s exact test was used to compare all other variables.