Sometimes shiki is tagged as a girl, sometimes as a boy. Going by the context of this comic, confusuin is understandable but I wish I could know which s/he originally is. Either way:
What does it matter if the baby is female, you talk as if there was a problem there. This isn't the Bible, girls are allowed to be born and live fruitful lives free of hatred or discrimination.
More along the lines that I think his family not only wants heirs, but MALE heirs. It's a common theme in oriental/asian cultures that males carry on the family bloodline, where as females, it ends with them.
I doubt he had any real Ill will against women when he/she made that comment.
Calm your tits their friend :)
Updated
Ah, it moved
Ahaha...With this...
things might work out fine...Well... regardless of how it happened, the pressure's off now