My partner is hurt & confused

My fiancé is really having a hard time because there's no explanation to our MC. He's really looking for answers & trying to figure out what he can do to prepare for another try. This pregnancy wasn't planned, but we didn't try to prevent it. He was excited from the start. He understands I have to heal, but he's looking for tips to have a healthy pregnancy next time. This was my first pregnancy but his third child & first MC.