The app has been designed to help parents-to-be with the collected wisdom of other parents, "who have been there and done that".
The partnership with Persil Non-Bio and Comfort Pure will cover co-branded advertising, new shareable and static content, sponsored discussions, a Mumsnet homepage take-over, extensive product testing and blogger reviews.
Mumsnet declined to release active user figures for the app as it has just been hard-launched, according to a spokeswoman.
Fernanda Tubini Roberts, a senior brand manager at Unilever, said: "Specially formulated for delicate skin, Persil Non-Bio and Comfort Pure are a favourite with parents as they help to care for and protect a baby’s sensitive skin, making this partnership a natural fit for us during this special time."
Persil and Comfort sponsor Mumsnet Pregnancy Tracker app

Unilever laundry brands Persil Non-Bio and Comfort Pure are to sponsor Mumsnet's new Pregnancy Tracker app for a year.