Complications of leaving the placenta can include residual bleeding, infection, bowel obstruction, pre-eclampsia (which may all necessitate further surgery) and failure to breast feed due to placental hormones. Outcome with abdominal pregnancy can be good for the baby and mother, Lampe described an abdominal pregnancy baby and her mother who were well more than 22 years after surgery. About 1.4% of ectopic pregnancies are abdominal, or about 1 out of every 8,000 pregnancies. A report from Nigeria places the frequency in that country at 34 per 100,000 deliveries and a report from Zimbabwe, 11 per 100,000 deliveries. The maternal mortality rate is estimated to be about 5 per 1,000 cases, about seven times the rate for ectopics in general, and about 90 times the rate for a "normal" delivery (1987 US data). Al-Zahrawi (936–1013) is credited with first recognizing abdominal pregnancy which was apparently unknown to Greek and Roman physicians and was not mentioned in the writings of Hippocrates; Jacopo Berengario da Carpi (1460–1530) the Italian physician is credited with the first detailed anatomical description of abdominal pregnancy. Because pregnancy is outside the uterus, abdominal pregnancy serves as a model of human male pregnancy or for females who lack a uterus, although such pregnancy would be dangerous. Abdominal pregnancy has served to further clarify the disease pre-eclampsia which was previously thought (1980's) to require a uterus for it to occur, however pre-eclampsia's occurrence in abdominal pregnancy (with the conceptus outside the uterus) helped throw light on pre-eclampsia's etiology. Cases of combined simultaneous abdominal and intrauterine pregnancy have been reported.