Mandatory IUDs for deployment would solve the issue, regardless of the intentions of the woman.
THAT would be an amazing PR move. Mandatory medical procedure with a risk of sterility.
No, the answer is to do exactly what we do currently. Train and deploy the soldiers we have. There are some medical conditions that make you non deployable (for men and women). You test for those pre deployment, and if a soldier gets a non-deployable condition while deployed you re-deploy them. It's not that big a deal, except to social engineering grad students and feminists with an article to write.
Yes it sucks when a soldier gets pregnant and redeploys early, because you have to cover down on their job. As you do when a soldier gets sleep apnea, hurts their knee, get's diagnosed with high blood pressure, or any of the literally two pages* of conditions that makes some one non-deployable.
We do have some issues integrating females, and some of them are self inflicted, but a rash of pregnancies isn't one of them, even malingering pregnancies.
*And the two pages is just for CENTCOM. Every AOR has their own list of things they won't allow.