Values are means +s.e.m. for the egg weight prior to incubation (A), the absolute fetal weight at the end of the incubation period (B) and the fetal weight at the end of the incubation period expressed as a percentage of the initial egg mass (C). SLSL (open bar, n = 31), SLHA (filled bar, n = 19), HAHA (stippled bar, n = 33), HASL (hatched bar, n = 30), and SLHA + O2 (grey bar, n = 26). Different letters are significantly different by one-way ANOVA with Student–Newman–Keuls or Dunn's tests, as appropriate (P < 0.05).