Birth control and education
Family planning, as well as the availability and use of contraception, along with increased comprehensive sex education, has enabled many to prevent pregnancies when they are not desired. Schemes and funding to support education and the means to prevent pregnancies when they are not intended have been instrumental and are part of the third of the Sustainable Development Goals (SDGs) advanced by the United Nations. Technologies and science
Assisted reproductive technology
Modern reproductive medicine offers many forms of assisted reproductive technology for couples who stay childless against their will, such as fertility medication, artificial insemination, in vitro fertilization and surrogacy. Medical imaging
Medical imaging may be indicated in pregnancy because of pregnancy complications, disease, or routine prenatal care. Medical ultrasonography including obstetric ultrasonography, and magnetic resonance imaging (MRI) without contrast agents are not associated with any risk for the mother or the fetus, and are the imaging techniques of choice for pregnant women. Projectional radiography, CT scan and nuclear medicine imaging result in some degree of ionizing radiation exposure, but in most cases the absorbed doses are not associated with harm to the baby. At higher dosages, effects can include miscarriage, birth defects and intellectual disability. Epidemiology
About 213 million pregnancies occurred in 2012 of which 190 million were in the developing world and 23 million were in the developed world. This is about 133 pregnancies per 1,000 women aged 15 to 44. About 10% to 15% of recognized pregnancies end in miscarriage. Globally, 44% of pregnancies are unplanned. Over half (56%) of unplanned pregnancies are aborted.
Women who have never carried a pregnancy more than 20 weeks are referred to as nulliparous.A pregnancy is considered term at 37 weeks of gestation. It is preterm if less than 37 weeks and postterm at or beyond 42 weeks of gestation. American College of Obstetricians and Gynecologists have recommended further division with early term 37 weeks up to 39 weeks, full term 39 weeks up to 41 weeks, and late term 41 weeks up to 42 weeks. The terms preterm and postterm have largely replaced earlier terms of premature and postmature. Preterm and postterm are defined above, whereas premature and postmature have historical meaning and relate more to the infants size and state of development rather than to the stage of pregnancy. Signs and symptoms
The usual signs and symptoms of pregnancy do not significantly interfere with activities of daily living or pose a health-threat to the mother or baby. However, pregnancy complications can cause other more severe symptoms, such as those associated with anemia. Common signs and symptoms of pregnancy include:

Tiredness
Morning sickness
Constipation
Pelvic girdle pain
Back pain
Braxton Hicks contractions. Occasional, irregular, and often painless contractions that occur several times per day. Peripheral edema swelling of the lower limbs. Common complaint in advancing pregnancy. Can be caused by inferior vena cava syndrome resulting from compression of the inferior vena cava and pelvic veins by the uterus leading to increased hydrostatic pressure in lower extremities. Low blood pressure often caused by compression of both the inferior vena cava and the abdominal aorta (aortocaval compression syndrome). Increased urinary frequency.