Preconception and post conception risks exist for both mother and child. The purpose of obstetrics is to maintain the health of the pregnant woman and to ensure optimal health of the fetus. Certain fetal and maternal conditions have been shown to have environmental and genetic components. Two determinations must be made when a physician responds to a patient's concerns about a specific exposure whether,

• Any quantity of the toxicant has known adverse effects on reproduction in humans.
• The substance is present in sufficient quantity to affect the patient or population exposed.

Hyperemesis gravidarum is the severe form of nausea and vomiting in pregnancy, not related to other causes that is associated with a measure of acute starvation, such as ketosis and weight loss. This condition may cause volume depletion, electrolytes and acid-base imbalances, nutritional deficiencies, and even death. Severe hyperemesis requiring hospital admission occurs in 0.3-3% of pregnancies.

The ability to intervene in the health of populations is dependent upon development of appropriate tools for measuring health, illness, interventions, and outcomes. Only by standardizing the communication, Doctors can hope to target high-risk populations with effective interventions. Therefore, understanding the common language of public health is vital.

Using anticoagulants and thrombolytics in pregnancy is an important consideration. Pregnancy is associated with a 5-fold increase in the risk of venous thromboembolism (VTE), with the risk rising to 20-fold or more during puerperium. The risk further increases if an underlying thrombophilia is present and the risk of VTE persists until nearly 12 weeks postpartum. For the treatment of acute VTE, valvular heart disease, prevention of pregnancy-related complications in women with antithrombin deficiency, antiphospholipid antibody (APLA) syndrome, or other thrombophilia who have had a prior VTE, Anticoagulant therapy is indicated in pregnancy.

Breech presentation can be defined as a fetus in a longitudinal lie with the buttocks or feet closest to the cervix. This occurs in 3-4% of all deliveries and the percentage of breech deliveries decreases with advancing gestational age from 22-25% of births before the 28 weeks' gestation to 7-15% of births at 32 weeks' gestation to 3-4% of births at term. Predisposing factors for breech presentation include prematurity, uterine malformations or fibroids, polyhydramnios, placenta previa, fetal abnormalities.

Endometritis is the inflammation of the endometrial lining of the uterus. Inflammation may involve the myometrium and, occasionally, the parametrium. Endometritis can be divided into pregnancy-related endometritis and endometritis unrelated to pregnancy (pelvic inflammatory disease (PID)).

Puerperium is the time from the delivery of the placenta through the first few weeks after the delivery, which is usually considered to be 6 weeks in duration. By 6 weeks after delivery, most of the changes of pregnancy, labor, and delivery have resolved and the body has reverted to the nonpregnant state.

Polymorphic eruption of pregnancy (PEP), described as pruritic urticarial papules and plaques of pregnancy (PUPPP), refers to a benign dermatosis that usually arises late in the third trimester of a first pregnancy. This had been reported as toxemic rash of pregnancy, toxemic erythema of pregnancy, and late-onset prurigo of pregnancy.

Post term pregnancy is the pregnancy that extends to 42 0/7 weeks and beyond. The reported frequency of post term pregnancy is approximately 3-12%. However, the actual biologic variation is likely less, because the most frequent cause of a post term pregnancy diagnosis is inaccurate dating of pregnancy. Risk factors of thus include primiparity, prior post term pregnancy, male gender of the fetus, and genetic factors.

The importance of nutrition in pregnancy cannot be overstated. The fields of obstetrics and nutrition have changed over the last few decades, greatly affecting recommendations for prenatal nutrition. It maintains maternal energy requirements, provides substrate for the development of new fetal tissues, and builds energy reserves for postpartum lactation. Nutrition mainly focus on weight gain and dietary intake in pregnancy.