I. What is placenta praevia? Placenta praevia refers to placental tissue covering the inner cervical opening, which may lead to heavy bleeding, preterm labor and the need for cesarean delivery. There is usually no obvious abdominal pain before bleeding, and there may be mild contractions and a feeling of abdominal cramping. Placenta praevia should be suspected if vaginal bleeding occurs in women who are pregnant at 20 weeks of gestation or more. Since vaginal palpation can cause heavy bleeding when the placenta is palpated, for women who have not yet undergone midtrimester ultrasonography, if vaginal bleeding occurs after 20 weeks of gestation, ultrasonography should be indicated before vaginal palpation to clarify the location of the placenta. Who are prone to placenta praevia? 1, previous history of placenta praevia: previous placenta praevia, recurrence rate of placenta praevia in second pregnancy is 4%-8%. 2, previous cesarean delivery: two systematic evaluations showed that previous cesarean delivery increased the risk of placenta praevia by 47% and 60%. The risk increases with the number of cesarean deliveries. The risk of placenta praevia is higher in deliveries following a cesarean section before delivery compared to previous cesarean sections at delivery. 3. Multiple pregnancies: One study showed that the prevalence of placenta praevia was 40% higher in twin pregnancies than in singleton pregnancies (3.9 and 2.8 cases per 1000 births, respectively). Another study showed that twin chorionic twin pregnancies had a higher incidence of placenta praevia than single chorionic twin pregnancies or singleton pregnancies. 4. Other risk factors include: increased number of deliveries, advanced maternal age, infertility treatment, history of previous miscarriages, previous uterine surgery (hysteroscopic surgery), maternal smoking, maternal cocaine use, male fetus, and non-white race III. Pregnancy considerations: 1. Bleeding risk assessment: It is not possible to accurately predict whether an individual patient will bleed, the gestational age of bleeding, the amount of bleeding, or the frequency of bleeding. The risk of bleeding increases if ultrasonography shows: placenta completely covering the endocervix, thick placental rim (>1 cm), presence of anechoic zone at the edge of the placenta covering the endocervix, and cervical length less than or equal to 3 cm. 2. Women with placenta praevia are advised to avoid vaginal intercourse and exercise after 20 weeks of gestation (or earlier if vaginal bleeding has occurred) and to reduce physical activity during the later stages of pregnancy. This is because these activities can cause uterine contractions, which can lead to bleeding. Vaginal intercourse can directly damage the placenta praevia, which can cause bleeding. 3. If you experience contractions or vaginal bleeding, seek immediate medical attention as there is a risk of severe bleeding and emergency cesarean section. 4.Long distance travel is not recommended. 5.If bleeding occurs, during the period of fetal preservation and expectant treatment, pay attention to keep bowel and stool open and avoid doing actions that add abdominal pressure (lifting heavy objects, holding the baby, etc.).