What the studies say
Relationship satisfaction drops on average after a birth. It is one of the most consistently replicated findings in relationship psychology, and it has two features people forget to quote: the drop is an average — so a share of couples never experience it — and it is larger for mothers, which is no mystery once you look at who gets up at night and whose career is interrupted.
The cause is not the child. It is three things at once: sustained sleep loss, the disappearance of time as a couple, and a division of domestic work that tips abruptly — often never to return to its previous balance. The couples who come through well are the ones who act on those three points, not the ones who love each other more.
The first months, concretely
- Sleep is shared explicitly. Alternating nights, or cutting the night into two blocks, produces two tired parents rather than one exhausted parent and one guilty one.
- Chores are re-decided, not carried over. The old split no longer holds; the one that settles in by default during leave becomes permanent if nobody renegotiates it on return to work.
- One protected hour together each week. Not romantic: logistical. It is the only moment you talk about something other than organisation.
- Ask for help early. A third person present a few hours a week changes more than any advice.
What is not tiredness
Sadness lasting beyond two weeks, loss of interest in everything, constant anxiety or frightening thoughts are not "the baby blues": postnatal depression affects roughly one woman in eight, and fathers too. It is treatable, and treated early it is short. Raising it with the doctor, the midwife or the follow-up clinic is not an overreaction. See mental health.
Parental leave changes the outcome
One point on which the data converge: when the second parent takes long, non-transferable leave, the division of chores stays more balanced years later, and the pay gap between the two widens less. That is not a moral effect but a habit effect: whoever has been solely responsible for an infant for eight weeks knows how, and carries on.
Length, pay and the share reserved for each parent differ completely from one country to the next — one of the subjects where the country page matters more than the article. See also childcare and what it really costs.
Becoming a couple again
Desire does not return on a fixed date, and not because you decide it is time. What brings it back is sleep first, then the sense of being two adults rather than two functions. See desire after a birth.