Constipation (constipation) is a common clinical symptom, including difficulty in defecation and / or reduced frequency of defecation, dry and hard stool, difficulty in defecation, feeling of inexhaustible defecation, feeling of anorectal obstruction, time-consuming defecation and need for auxiliary defecation. Reduced defecation means defecation less than 3 times a week.Constipation is very common during pregnancy, and studies have found that the incidence of constipation in pregnant women is as high as 40%. Among them, the prevalence of functional constipation in the early, middle, late and postpartum pregnancies is 35%, 39%, 21% and 17% respectively, with the highest in the early and middle pregnancies.Constipation can increase the psychological burden of pregnant women and affect their quality of life. Long-term severe constipation can also induce or aggravate hemorrhoids. Severe constipation can induce uterine contractions, which will adversely affect the pregnancy outcome of pregnant women.Studies have found that there is a difference in the abundance of intestinal flora between patients with constipation during pregnancy and pregnant women without digestive tract diseases.Although microecological preparations are not front-line drugs for the treatment of chronic constipation, they can promote intestinal peristalsis and the recovery of gastrointestinal motility by regulating the imbalance of intestinal flora. More and more researchers recommend them as long-term adjuvant drugs for chronic constipation. Probiotics are a type of microecological preparation, which refers to living microorganisms that can have beneficial health effects on the host after ingesting a sufficient amount.It is relatively safe to supplement probiotics during pregnancy.Our research team found a probiotic strain, Lactobacillus reuteri DSM17938+, which has no significant difference in improving constipation symptoms in patients with constipation compared with lactulose, and is even more effective than lactulose in alleviating abdominal pain and flatulence symptoms.However, clinical studies proving that Lactobacillus reuteri DSM17938 + is effective on constipation are generally concentrated abroad, and mainly focus on infants and young children, children, adults\] or intestinal colic. Data on maternal population in China is lacking.