Sciatica can be very common in pregnancy and will often come and go throughout the pregnancy. It is most common in the third trimester as the body loosens ligaments (to prepare the body for birth) and stretches as it takes on additional weight.
Causes of sciatica in pregnancy can be from an expanding uterus, fluid retention, weight gain of mom and baby, and/or the baby’s head as it settles into the proper birth position. All of these changes can put pressure on and compress the sciatic nerve.