Usually around 50% of those who are pregnant develop some sort of foot pain during pregnancy. There are a number of reasons for this. The most obvious reason is the increase in weight during the pregnancy puts a greater load on the feet and the feet just break down under those loads. Also during pregnancy the feet and ankles swell which can lead to problem, especially with the fit of footwear. Hormonal changes during the pregnancy, especially the hormone relaxin affects the ligaments in the body and in the foot can affect foot function which increases the risk for foot problems during pregnancy.
To relieve some of the generic foot pains that happen during pregnancy, it is advisable to do plenty of strengthening and stretching exercises for the foot and legs. It is preferable if this can start before the pregnancy and the increase in weight.
It is also advisable to wear roomy, yet supportive footwear and even go up a size in shoes if the feet start to swell. The wearing of compression hosiery and rest with the feet up may be needed to deal with the swelling.
Getting some arch supports or something similar into supportive and roomy shoes may also give the feet the support they need to deal with the weight gains that happen during the pregnancy.
Foot massages from the partner are widely considered as being essential during a pregnancy to help relieve foot pain during the pregnancy. It can also help deal with some of the swelling that occurs and can also be very relaxing.