How many months is 18 weeks of pregnancy?

At 18 weeks of pregnancy, you are approximately four and a half months along. This marks the beginning of the second trimester, during which the fetus has generally become more stable. It is appropriate to engage in moderate exercise at this stage. Meanwhile, the fetus continues to develop and mature; therefore, it is essential to follow your healthcare provider’s recommendations for routine prenatal checkups—including a 4D ultrasound to assess fetal development and a Down syndrome screening test.