In fact, you can have a very nice weather in a high pressure zone, with clear sunny sky and little wind, but during daytime, the pressure drops a little to climb up again during the night. That is a normal diurnal variation of pressure; when it is hot, air rises and pressure drops a bit. It is not the drop in itself but the rate of fall that is the most important point and that's why some people have barographs that register the pressure over time. An old seafarer's rule is that a pressure fall of ten millibars (today, called hecto-Pascal) in eight hours is a certain sign of a gale force wind coming in. And that is the only thing that is 100 percent certain in meteorology; a pressure fall must be followed by a wind of air trying to fill again the lower pressure.
Overview. 1  Babies can develop enlarged kidneys -- a condition known as hydronephrosis -- while still in the womb, or after birth. This condition is the most frequently discovered problem revealed by ultrasound examinations of babies in the womb.
In pregnant women, hormones cause changes in the urinary tract, which predispose women to infections. In addition, a growing uterus presses on the bladder, preventing the complete emptying of urine. This stagnant urine is a likely source of infection. Untreated, these infections may lead to kidney infections. Urinary tract and kidney infections in pregnant women should be treated to prevent complications.