The basic outlines of the organ, body, and nervous systems are established.
By the end of the embryonic stage, the beginnings of features such as fingers, eyes, mouth, and ears become visible.
After the point of fertilization, the fused product of the female and male gamete is referred to as a zygote or fertilized egg.
In the case of a multiple birth the gravida number and parity value are increased by one only.
Women who have never carried a pregnancy achieving more than 20 weeks of gestation age are referred to as nulliparous.
A woman who is (or has been only) pregnant for the first time is referred to as a primigravida, Therefore, during a second pregnancy a woman would be described as gravida 2, para 1 and upon live delivery as gravida 2, para 2.
In-progress pregnancies, abortions, miscarriages and/ or stillbirths account for parity values being less than the gravida number.
Fertilization can also occur by assisted reproductive technology such as artificial insemination and in vitro fertilisation.
Fertilization (conception) is sometimes used as the initiation of pregnancy, with the derived age being termed fertilization age.Fertilization usually occurs about two weeks before the next expected menstrual period.A third point in time is also considered by some people to be the true beginning of a pregnancy: This is time of implantation, when the future fetus attaches to the lining of the uterus.Also during this time, there is development of structures important to the support of the embryo, including the placenta and umbilical cord.The placenta connects the developing embryo to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply.Sometimes, timing may also use the fertilization age which is the age of the embryo.