Book with cows as incubators

You might be looking for Frederik Pohl's Outnumbering the Dead. While the main plot is about humanity being rendered immortal prior to birth, and the main character, Rafiel, being a rare case of the procedure failing (and thus him being doomed to die eventually), there is a sub-plot where he discusses having a baby with Alegretta and indeed, the embryo is incubated within a cow at a creche.

Searching for science fiction novel embryos cow creche got me a Google Books excerpt from The Best of the Best, Volume 2: 20 Years of the Best Short Science Fiction. Searching for some keywords from there, sonora arcology rafiel alegretta, found me an online copy of the issue of *Asimov's* that contained the story. Here is an excerpt from page 244 and page 258:

She was waving a tomograph, and when she handed it to him he was astonished to see that it was an image of what looked like a three-month fetus. He blinked at her in surprise. “Yours?”

She nodded ecstatically. “They just sent it from the creche,” she explained, nervous with pleasure. “Isn’t it tres belle?"

…

Then it was Rafiel’s turn to blunder. “What sort of surrogate are you using?” he asked, to make conversation, and she gave him a sharp look.

“Did somebody tell you? No? Well, it’s cow,” she said, and waited to see what his response would be. She seemed aggrieved. When all he did was nod noncomittally, she said, “Charlus wanted to use something fancier. Do you think I did the right thing, Rafiel? Insisting on an ordinary cow surrogate, I mean? So many people are using water buffalo now. . . .”

It's a slightly weak match, in that this is a brief scene in the book, and they actually only use the word "creche" once, but it does match your question. If this is not the correct answer, it would be helpful for you to edit the question with details that you now know because they do not match this book.