Conceptional Age

Definition - What does Conceptional Age mean?

Conceptional age refers to the age of the fetus from the day of conception, when a sperm fuses with the egg and the early developmental stages of a fetus start. In most spontaneous pregnancies, determining the exact date of conception is difficult, and it is usually assumed that the conceptional age is 2 weeks (11-21days) less than the gestational age.

When the pregnancy is achieved by assisted reproductive technologies such as in vitro fertilization (IVF), it is possible to pinpoint the date of conception and thus the conceptional age.

FertilitySmarts explains Conceptional Age

Gestational age is the age from the first day of the last menstrual period and is the most widely used method of determining the age of the fetus. This is also known as the postmenstrual age. Gestational age is usually 2-3 weeks longer than the conceptional age.

Gestational age and conceptional age are the two main methods of determining an age of a fetus during pregnancy. These methods can have slight variation due to the fact that the exact date of fertilization and implantation of the embryo can only be estimated, unless in specific circumstances like assisted reproductive technologies.

An ultrasound is usually performed a few weeks after the confirmation of pregnancy to confirm the calculated gestational age or when a menstrual history is not clear enough to calculate a gestational age. Ultrasound scanning is most accurate to determine the fetal age between 8-18 weeks of pregnancy. The accuracy gradually declines as the pregnancy progresses beyond this point.

After a full-term birth, calculation of the chronological age typically begins from the date of delivery.

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