Doku's wife Shireen is due to give birth during the second week of July and he intends to return home even if the Red Devils are still in the tournament, which would then be at the quarter-final stage.
"It's my first child, so I would definitely want to be there," the Manchester City forward, 24, told Reuters, external.
"If you ask me what I want, my answer is that nobody wants to miss the birth of their first child. But I also know that football involves many other considerations.
"I know the federation supports its players and understands their situations. We'll see what we can do."
However, Doku's plan to leave the USA and return home has brought fierce criticism from L'Equipe channel presenter France Pierron, who labelled a father "completely useless" at the time of their child's birth.
"The World Cup is an incredible joy," she said in a message posted to the Facebook page of French sports publication L'Equipe.
"There are hundreds of footballers who would kill to be in your shoes. It might never happen again in your life.
"You're living out a childhood dream, yet you're going to walk away from it all to attend the birth of your child - a disgusting moment, if you'll pardon the expression, where the dad is completely useless."
'A baby is your entire life'
Doku has received plenty of support online following Pierron's remarks - including from retired boxer Brahim Asloum, who won light-flyweight gold for France at the 2000 Sydney Olympics.
"A baby is your entire life. A World Cup is over when it is over," he wrote.
Later on Saturday, Pierron released a statement on her X page in a bid to explain her comments and apologise for any offence caused.
"I was expressing a personal opinion, within the context of a contentious exchange," she said.
"I understand that they may have shocked, hurt, or wounded some of you, and I am sorry for that.
"My intention has never been to minimise the place or role of fathers with their partner and their child."
Belgium confirmed on Saturday that Doku will miss their second World Cup group match against Iran (20:00 BST) because of illness. Rudi Garcia's side drew their opening game with Egypt 1-1.
