Hello,
Welcome to the ehealthforum and I am really glad to help you out. Your concern is regarding the abdominal cramps that your wife is having in the second trimester. This is common during pregnancy because of the hormones and uterine growth due to the fetal growth which pulls the ligaments of the uterus but if she is having severe cramps then they need urgent evaluation.
Meanwhile she should eat a healthy, nutritious diet, exercise moderately and take plenty of rest. But if the symptoms are severe then please consult your gynecologist and she should not take any medicines on her own as none of the medicines are safe during pregnancy. Also keep an eye on spotting, bleeding, fever, chills, dizziness or discomfort while urinating.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.