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.
It depends on your cycle length and when you ovulate. You are at your most fertile the day you ovulate and the day before (generally 12-16 days before your next period starts). But donât forget that sperm can survive for several days, so even if you have sex a few days before you ovulate, you could still get pregnant.