Artus, 2015, explains the Hanafi stance: "marriage is legal at any age... sexual intercourse between the husband and the wife happens after the girl reaches puberty". Islam Q&A instead says "until she is physically able to bear intercourse". In any case, as far as I can tell, it's possible for a Muslim man be married to a 13 or 14 year-old girl, say, and have sex with her legally under Sharia.
Question: Is it haram for a husband to get his 13 or 14-year-old wife pregnant?
I ask because there seems to be medical and social complications that can arise from pregnancy at that age, e.g.:
The top three causes for maternal death in Pakistan are post-partum haemorrhage (excessive bleeding), sepsis (major infection) and eclampsia (hypertensive disorder). All three are found to have greater prevalence in teen pregnancies due to biological and physiological factors. -- Mumtaz et al., Age of marriage: A position paper, 2010 (pdf)
And I wonder if it's haram until she is physically able to bear pregnancy (analogous to the Islam Q&A fatwa).