Period | Mean maternal age in years (SD) |

Period A | 34.07 (3.89) |

Period B | 34.28 (3.90) |

Period C | 34.69 (3.98) |

Period | Average fetal weight in grams (SD) |

Period A | 3119.13 (538.19) |

Period B | 3149.68 (546.93) |

Period C | 3149.60 (541.03) |

Period | Average gestational age in weeks (SD) |

Period A | 38.42 (2.05) |

Period B | 38.14 (2.01) |

Period C | 38.57 (1.93) |

Period | Multiple pregnancy rate in % (SD) |

Period A | 3.58 (0.87) |

Period B | 3.54 (0.78) |

Period C | 3.43 (1.06) |