When Did Conception Occur?
Many women ask this question when trying to determine the exact day they became pregnant. The fetal age, or age of the fetus, is often calculated from the first day of the mother's last menstrual period. Biologically, fertilization of the egg does not occur until ovulation and egg fertilization, which usually happens at least 10 days after the first day of the mother's last menstrual period.
Due to various factors surrounding conception, it is challenging to pinpoint the date of conception accurately. This calculator helps estimate the actual date of conception and a possible range of days when sexual intercourse can lead to conception. There are several methods that can be used to estimate conception dates.
Last Menstrual Period
Conception typically occurs between 11-21 days after the first day of the last menstrual period for women with regular cycles. Estimating the date of conception is based on this range but is rarely completely accurate because it is difficult to know precisely when ovulation occurs. Estimating fetal age can be even more challenging for women with irregular cycles or those who don't remember the first day of their last menstrual period. In such cases, one of the most accurate methods to estimate fetal age is through the use of ultrasound.
Fertilization, Conception, and Pregnancy
Fertilization and conception are terms often used interchangeably, but this calculator uses definitions preferred by doctors and scientists. Fertilization occurs when a sperm cell and an egg unite in the fallopian tube, forming a fertilized egg, thus initiating the process in which the fetus develops.
Conception refers to the process of pregnancy, which scientifically includes both fertilization and the implantation of the fertilized egg into the uterine wall. On a state level (in the United States), there can be some confusion in the use of these terms due to varying definitions. In some cases, a woman is considered pregnant after fertilization, but this does not align with well-established scientific and medical definitions. The long-standing consensus among medical professionals and government policies (in the United States) is that a woman is pregnant when the fertilized egg is implanted in the uterine wall. When this occurs, the woman is said to be "with child." In other words, medically and scientifically, conception involves both fertilization and implantation, and a woman is not considered pregnant until both of these events have taken place.
Last Review Date: 09/07/2023