Why do they say the first three months are trimester 4? What should I be expecting?

The fourth trimester is simply the three months after postpartum where the mother is healing and baby is adjusting to life outside the womb. For the mother, you may experience some swelling immediately after birth. Drink more fluids and elevate your legs whenever possible to help ease the water retention. There will also be vaginal soreness (could last up to six weeks from delivery). You can try sitting on donut pillows to help provide more cushioning yet minimizing direct contact to the vaginal region. My colleague sat on a swimming float for a couple of weeks. Though not as comfortable but worked for her. Vaginal bleeding will take place and will likely last up to six weeks or so. There will be breast engorgement as your body figures out how much milk to produce. Wearing a well fitted supportive bra, nursing on demand and applying cold cabbage leaves will help ease the discomfort. Some mothers also experience bladder issues such as incontinence. Doing kegel exercise may help strengthen the kegel muscles and push the bladder back up. Make use of the confinement period to get enough rest and allow time for your body to recover. It is also good to keep the baby close during this period of time to help the baby adjust. Sing, talk and read to your baby. Having more skin-on-skin contact will also help comfort the baby. For some useful information on the fourth trimester, you can take a look at this article: http://thrivinghomeblog.com/2013/07/understanding-the-fourth-trimester/