Seeing red on the 40th day of pregnancy, but the bleeding is relatively small, it may be a symptom of preterm miscarriage, but it does not exclude ectopic pregnancy, uterine horn pregnancy and other ectopic pregnancy, so if you plan to have this baby, come to the hospital as soon as possible to do an ultrasound to see, to make sure that the pregnancy is in the uterus, and to exclude the case of ectopic pregnancy. In addition, take blood tests for HCG, progesterone and estradiol to check the hormone levels, and use progesterone intramuscular injection or oral progesterone capsules as soon as possible to protect the fetus, and at the same time take oral natural vitamin E and Anfrancipation pills to protect the fetus, have more bed rest, move as little as possible, and eat more fresh vegetables and fruits, and eat less spicy and stimulating food. If the bleeding is getting more and more, turning into bright red or accompanied by severe pain in the stomach, it may be an inevitable miscarriage, which should be dealt with in the hospital as soon as possible.