- Conception occurs with the union of the sperm and ova.
- Both the sperm and the ovum will bring to the union a nucleus with 23 chromosomes, 22 somatic (body) chromosomes and a sex chromosome, either an X or Y from the sperm and an X from the ovum.
- When the sperm fertilizes the ovum, the sex of the baby is determined and the resulting zygote contains 46 chromosomes with the characteristics of both the mother and the father.
- The normal gestation lasts 40 weeks.
- The diagnosis of pregnancy is based on the signs of pregnancy. The signs of pregnancy are categorized as probable, presumptive, and positive based on their significance in the diagnosis.
Warning signs of Pregnancy: The pregnant woman is given a list of “warning signs” that require immediate notification of the physician (see Table).
Warning Signs of Pregnancy
|Symptom||Time of Occurrence||Possible Interpretations|
|Severe vomiting||Anytime, especially in the first and second trimesters||Hyperemesis gravidarum|
|Burning on urination||Anytime||Urinary tract infection|
|Abdominal cramping or pain||Anytime||Miscarriage, ectopic pregnancy, or abruptio placenta|
|Vaginal bleeding||Anytime||Miscarriage, ectopic pregnancy, abruptio placenta, or placenta previa|
|Sudden gush of fluid from the vagina, uterine contractions||Before 37 wks||Premature rupture of the membranes|
|Absence of fetal movement||Second and third trimesters||Fetal demise|
|Epigastric pain, muscular irritability, convulsions, headache, visual disturbances, or edema of face and hands||Second and third trimesters||Pregnancy-induced hypertension|