To put a twist on the idea... there's a lot of in-person tech meetups and conferences thesedays that provide childcare during the meet itself so that parents can attend.

Offer to sponsor the childcare facilities during these events. The meetup/conference organisers will bite your handoff since you're directly covering the cost of something which will boost attendance.

In return you get to pitch directly to parents in tech, who can become advocates of your service to their own HR departments.

Depending on your budget, you could also offer the parents who use the facilities a free coupon for X hours of childcare on your platform, that way, you can review the stats of those who use the service later. If you notice a few folks from one particular company, then you have a warm approach to their HR department in the form of "X number of your employees are already onboarded".