expect their first child September 5

[sitifan]

1. They're expecting their first child September 5.
2. They're expecting their first child on September 5.
Which of the above sentences is correct?

[Gentle Nguyen]

I'm not a teacher.

be expecting a child/ baby = be pregnant

So if you want to say that the child will be born on Sep 5 you can say:

They’re expecting their first child who will be born on September 5.

My opinion is a reference. Let’s see other person’s suggestions

[Tdol]

The second sounds better to me.

[5jj]

be expecting a child/ baby = be pregnant

It can also used in the sense of 'expecting to give birth to'. So, 'They are expecting a child in September' is fine, as is:

2. They're expecting their first child on September 5.

[Rover_KE]

I hardly need add that most babies decide for themselves when to emerge into the light, so a due date of 5th September is widely understood to mean early in September.

Rover