If women have the same physical potential as men, this means that the peasant wife can now be very productive during the planting and harvest… not as productive as the man, since some of her time will still be spent trying to deliver babies, but say about 80% or so. Ths raises the female peasant from the role of “dependent breeder” to an important part of the agrarian community. This means that there is less waste and overhead for the peasantry, resulting in a higher surplus yield, which means you have more people with free time.

This would have interesting effects along with the magic and/or technology greatly reducing infant and childhood mortality. You’d probably get even more productivity out of women, although you’d likely also get a rise in various ways of eliminating excess births (like contraception, abortion, and infanticide).

Combine the above two with reasonably reliable magical contraception, and you’d end up with a very interesting looking medieval society. It would likely be an older one, as well, simply because children would be less common, and there would be more old people due to the significantly less early childhood mortality (which was the real reason you generally see statistics like “medieval people had a life expectancy of 30 years”. It’s not that they dropped dead at 30 – rather, infant mortality was very high, but if you survived your childhood you’d likely live into your 50s and 60s barring disease, injury, or war).