If a pregnant woman has a hard tummy at 16 weeks of pregnancy, the cause needs to be specifically analyzed. It may be caused by uterine contractions or gastrointestinal reactions, but it may also be caused by an abnormal pregnancy, and patients need to be alert to the complication symptoms in case of hardness and seek medical attention for symptomatic treatment in a timely manner. Common causes and treatments: 1. Pseudocontractions: mainly spontaneous, painless contractions of short duration that promote blood circulation in the uterine blood sinuses and chorionic gaps. They usually do not cause abdominal pain and vaginal bleeding and can last until delivery. Usually no special treatment is needed, but proper rest and regular obstetric checkups are required. 2. Gastrointestinal reactions: As the uterus gradually expands into the abdominal cavity during pregnancy, when the uterus pushes the stomach to other parts. Since there is a certain delay in gastric emptying after the pregnant woman eats, the symptoms of occasional hardness and tightness in the upper abdomen may also occur. Generally, it can be relieved with the gradual digestion of food and does not require special treatment. 3. Pre-eclampsia: When the contraction of the uterus cannot be suppressed, tightness and hardness of the abdomen appear frequently, or accompanied by vaginal bleeding, abdominal pain and other symptoms, it may indicate pre-eclampsia. At this time, you need to go to the hospital in time, through ultrasound and other examinations to clarify the cause, and then according to the disease, under the guidance of professional doctors for symptomatic treatment, such as pre-eclampsia can use progesterone to perform anti-fetal treatment, if necessary, to terminate the pregnancy. Note: Pregnant women need to pay attention to rest, avoid overexertion, try not to do heavy physical activities, do not eat garlic, onions and other spicy stimulating food, so as not to induce contractions.