The kidney is not one large filter. Each kidney is made up of about a million filtering units called nephrons. Each nephron filters a small amount of blood. The nephron includes a filter, called the glomerulus, and a tubule. The nephrons work through a two-step process.
Generally speaking, first babies tend to engage from about 34 weeks to 36 weeks. However, some babies only engage once labour starts. Try not to worry, though. Even if your baby hasn't engaged by the time labour starts, in most cases, it's not a problem.
Of all couples trying to conceive: 1  30 percent get pregnant within the first cycle (about one month). 2  59 percent get pregnant within three cycles (about three months). 3  80 percent get pregnant within six cycles (about six months). 80 percent get pregnant within six cycles (about six months). 2  85 percent get pregnant within 12 cycles (about one year). 3  91 percent get pregnant within 36 cycles (about three years). 4  93 to 95 percent get pregnant within 48 cycles (about four years).