A note about language and inclusivity. I’ll be talking about birth parent and non birth parents to be inclusive of all families, but I'll also be using terms specific to sex/gender where relevant. Where I mention men and women, it's often because there is specific data from sex science, (almost always referring to cis men and women -people whose gender identity matches the one they were assigned at birth).

Trans and non-binary people- there is a lack of research into sex for new parents in trans and non binary communities so although much of this data will fit you just as well, please accept my apologies for the lack of specific mention here, I’m very aware of the limitations of the binary nature of sex science and the cisheterocentric research into parenthood.