Abortion is the removal of an embryo or a fetus before it is able to survive outside the uterus. Spontaneous abortion is identified as the unintentional expulsion of an embryo or a fetus before the 24th week of pregnancy. About 50% of miscarriages are attributed to chromosomal aberrations such as structural changes or abnormal chromosomal numbers. The increased age of more than 35 years for both partners has a considerable role in adverse pregnancy outcome and is 50% significantly higher if the age of the mother is 42 years or more. Other factors such as ethnicity, psychological status of the female partner, feeling of stress, hormonal abnormalities, very low or very high body mass index (BMI), infectious diseases, use of non-steroidal anti-inflammatory drugs, smoking and addiction to alcohol have also been correlated with recognizably higher rates of spontaneous abortion or miscarriage. Premature birth or preterm birth is the condition where pregnancy ends before 37 weeks of gestation resulting in a live-born infant. Stillborn is a term refers to the fetus that dies in utero after viability or during delivery.