Birth control pills should be used with caution in women who are over 40 years of age, over 35 years of age if they have a smoking habit, epilepsy, psychotic depression, abnormal menstruation, lactation, and those with mild hypertension. Since the drug can be secreted through breast milk, which has certain effects on the fetus, and the drug itself can reduce the amount of milk and make the protein-fat content of breast milk decrease, it is not advisable to take contraceptives during breastfeeding. Most of the short-acting oral contraceptives sold in the domestic market are made of estrogen and progestin. Among them, estrogen can cause fluid in blood vessels to transfer to the tissue interstices, causing edema in the body of women taking the drug along with a decrease in circulating blood volume, slower blood flow and increased blood coagulation, resulting in higher blood pressure, increased risk of thrombosis, and higher incidence of myocardial infarction and stroke. The progestins in the drug can cause elevated blood lipids. Women with a history and family history of obesity, hypertension, hyperlipidemia, diabetes, thrombophilia, tumors and liver and kidney disease, smoking, especially at an older age (35 years or older), and breastfeeding are not recommended to use the combination oral contraceptive pill. Meng Fan said that these women can use condoms, IUDs, etc. Foreign clinical trials have shown that if an increase in blood pressure occurs after taking the pill, most will return to normal after stopping it immediately. It is best for those taking the pill to have their blood pressure measured and liver and kidney functions checked regularly. In terms of smoking as a single factor, its adverse cardiovascular effects should not be underestimated. Smoking damages the vascular endothelium, increases the activity of the procoagulant system, and increases the viscosity of the blood. When combined with the effects of estrogen, the risk of blood clots and cardiovascular and cerebrovascular infarction is even higher. Birth control pills regulate the cycle of your menstruation. A small amount of vaginal bleeding after taking the pill is not a sign of successful contraception. If there is no menstrual-like bleeding, you should go to the hospital early for examination.