Often labor has to be induced for medical reasons; such conditions include high blood pressure, pre-eclampsia, maternal diabetes, asthma, thyroid disease, and heart disease. Certain medical conditions in the pregnant mother may also increase the risk of preterm birth. Some women have anatomical problems that prevent the baby from being carried to term. These include a weak or short cervix (the strongest predictor of premature birth). Women with vaginal bleeding during pregnancy are at higher risk for preterm birth. While bleeding in the third trimester may be a sign of placenta previa or placental abruption—conditions that occur frequently preterm—even earlier bleeding that is not caused by these conditions is linked to a higher preterm birth rate. Women with abnormal amounts of amniotic fluid, whether too much (polyhydramnios) or too little (oligohydramnios), are also at risk. Anxiety and depression have been linked as risk factors for preterm birth.The use of tobacco, cocaine, and excessive alcohol during pregnancy increases the chance of preterm delivery. Tobacco is the most commonly used drug during pregnancy and contributes significantly to low birth weight delivery. Babies with birth defects are at higher risk of being born preterm.Passive smoking and/or smoking before the pregnancy influences the probability of a preterm birth. The World Health Organization published an international study in March 2014.Presence of anti-thyroid antibodies is associated with an increased risk preterm birth with an odds ratio of 1.9 and 95% confidence interval of 1.1–3.5.Intimate violence against the mother is another risk factor for preterm birth.Physical trauma may case a preterm birth.
Notable cases
James Elgin Gill (born on 20 May 1987 in Ottawa, Ontario, Canada) was the earliest premature baby in the world, until that record was broken in 2004. He was 128 days premature (21 weeks 5 days gestation) and weighed 624 g (1 lb 6 oz). He survived.In 2014, Lyla Stensrud, born in San Antonio, Texas, U.S. became the youngest premature baby in the world. She was born at 21 weeks 4 days and weighed 410 grams (less than a pound). Kaashif Ahmad resuscitated the baby after she was born. As of November 2018, Lyla was attending preschool. She had a slight delay in speech, but no other known medical issues or disabilities.Amillia Taylor is also often cited as the most premature baby. She was born on 24 October 2006 in Miami, Florida, U.S. at 21 weeks and 6 days gestation. This report has created some confusion as her gestation was measured from the date of conception (through in vitro fertilization) rather than the date of her mothers last menstrual period, making her appear 2 weeks younger than if gestation was calculated by the more common method. At birth, she was 23 cm (9 in) long and weighed 280 g (10 oz). She had digestive and respiratory problems, together with a brain hemorrhage.