Pregnancy is not considered a disabling impairment for the purposes of Social Security disability, even if you have a high-risk pregnancy and significant physical impairments. This is true first of all because of the durational requirement for disability benefits. The durational requirement states the your condition must have lasted or can be expected to last a year or more before it is considered as part of your disability. Pregnancy lasts 9 months.
However, any permanent condition that you develop as a result of your pregnancy could be counted as part of your disability claim. For instance, if you had heart failure around the time of your delivery and you continue to suffer from chronic heart failure, of course that could cause you impairments of function that are disabling and could be counted as part of your disability claim. Your disability will be evaluated on the basis of the chronic condition you have rather than on the basis of pregnancy.