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There are various reasons for stomach pain during pregnancy.Is the pain present everytime,is it related to food intake,is it present in lower abdomen?Some of the common causes are gas formation,Urinary tract infections,increased BP and stretching of the uterine ligaments.At around end of second trimester you might experience false labour contractions which are perceived as abdominal pain.
Any kind of pain at this stage should not be ignored and needs proper attention.
Kindly visit your Gynaecologist for evaluation.
Take Care!