Briefly, based on the mean birthweight and variation at 40 weeks of gestation at each country, country-specific, equation-derived (i.e., not empirical) birthweight reference percentiles at 75th, 90th, 95th and 97th for each gestational week were generated.
It should be noted that mean birthweight of stillbirths is significantly below 500 g at 22 completed weeks.
At 40 weeks gestation, the mean birthweight of Australian live born twins are markedly lower than Norwegian and Finnish counterparts [ 15, 17] but the median birthweight of Australian twins are heavier than Canadian and Japanese twins [ 14, 16].
The mean birthweight of 3,267 singletons was 2,694 g and at 54 months of follow-up, the mean weight was 13.8 kg, and the mean height was 99.8 cm, with no significant differences among groups.
No difference appeared in the mean birthweight and after the litter size was equilibrated to 11 12 pups at birth, the evolution of the mean litter weight was identical regardless the maternal diet until weaning (results not shown).
Similarly, we found no difference in mean birthweight centile, birth weight adjusted for maternal body mass index, gestation at delivery, infant's sex, or ponderal index at birth between the two groups (table 2).
At gestational ages of less than 34 weeks, the mean birthweight of twins was 150 grams lighter than that of singletons.
Clinically important outcomes: preterm birth (delivery at < 37 weeks gestation); low birthweight (< 2500 g); mean birthweight; cord blood anaemia; adverse events.
The infants were born at a mean of 39 weeks of gestation with a mean birthweight of 3391 grams.
The median gestational age at birth was 40.1 weeks (minimum, 22.7; maximum, 43.4 weeks), while mean birthweight was 3450g (SD 549g).
