Can't risk worsening. It was said, falsely, that pregnancy protects mood. In fact, stress between pending parents, psychological tensions of moving from adult child to parent, fear of the unknown, &possibly hormonal changes all can feed depression in pregnancy. The depression can hurt prenatal care, it can offer physiological harm to mother and fetus, &it's the number1risk for post-partum depression (a true emergency).So treat.
Depression pregnancy. Some depression does get better in pregnancy but you can't count on it. Having depression at any time raises the risk of it being a problem after birth. Exercise and nutrition (esp omega 3s and folic acid) and working on cultivating relationships with others (especially your mother, the baby's father and other pregnant women) also may help.