It is generally considered safe to have sex during the 18th week of pregnancy, as long as there are no complications or medical conditions that would advise against it. However, it is always best to consult with your healthcare provider before engaging in any sexual activity while pregnant. They can provide personalized guidance based on your specific situation. If you have a low-risk pregnancy and are experiencing a healthy pregnancy without any complications, then there is usually no reason why you cannot enjoy a healthy sex life during this time. However, it's important to listen to your body and communicate with your partner about any discomfort or concerns you may have. Additionally, certain positions may be more comfortable than others as your belly grows larger. Remember that every pregnancy is unique, so what works for one person may not work for another. Ultimately, trust your instincts and prioritize open communication with your healthcare provider throughout your pregnancy journey.