Some pregnant women pregnant with twins do not appear to be late, some pregnant women pregnant with twins appear to be late for these reasons: 1, female ovulation time is late factors, if a woman in the preparation for the period of ovulation is late, then it will be followed by the result of the receipt of fertilization eggs in the late. It is also possible that the ovulation time in the month of pregnancy has been delayed, so it causes the bed to be late. 2, fertilization time is late, the preparation stage, although the timely discharge of the egg, but and the male sperm meet the time is late, this situation will affect the fertilization of the egg’s natural bed time, so the fertilization of the egg will be late. 3, women’s ovary luteal insufficiency, if in the preparation for pregnancy in the body of the female ovary If the ovary is not functioning properly, the endometrium will be abnormal, which will affect the time of the combination of egg and sperm, resulting in late fertilization of the egg.