The journey of life is one that starts well before birth and entails an amazing, intricate process of fertilisation, growth and development within the life-giving environment of a woman's womb (or uterus). By the time your baby is born, they will have already experienced around 9 months of life. Beginning as 2 cells merging (an ovum and sperm), their genetic programming instructs each cell to multiply, divide and differentiate into the various muscles, bones and organs of a male or female human body. It takes around 266 days (or 38 weeks) for a baby to develop to a stage where they can live independently from their mother. A breathtaking process!
From conception to 12 weeks a truly magnificent feat of biology takes place. This time is medically referred to as the '1st trimester'. By the start of the 13th week, most of your baby's organs are either formed, or well on the way. The following is a summary of the miracle that is unfolding within your body (or within your partner's body) and how your baby is developing during those first 12 weeks of pregnancy. A time of rapid change and growth.
NOTE: This pregnancy time scale is based on the woman having a 28 day menstrual cycle. We have chosen to go by 'completed weeks of pregnancy' but we have also stated the start of each week, because we describe what your baby will do over the following week. For example, if you are 4 weeks pregnant, you are at the start of week 5.
Bear in mind these descriptions are just a guide. A normal pregnancy can last anywhere from 37 to 42 weeks and your baby may not be at the exact described stage during each specified week. Every woman and her baby are different and the time of conception is the starting point, but the timing of this can vary depending on a woman's cycle, when she ovulates and the meeting of sperm and egg.