The 3rd trimester officially begins at the end of week 28 and lasts until your baby is born. A baby is regarded as being born 'on time' if they arrive between 37 completed weeks of pregnancy (or the start of week 38) and 42 completed weeks of pregnancy (14 days after the due date). However, many caregivers will recommend inducing babies that are 10 to 12 days overdue.

During the last months of pregnancy most women start to feel heavy and tired, as their baby increasingly takes up more space in their belly. This contributes to many of the physical signs of late pregnancy (such as heartburn, varicose veins, fluid retention and backache). By the time your baby is due, you may be feeling fed up with being pregnant and just want your baby to arrive soon!

During the final weeks of pregnancy, your baby's main task is to mature their body systems, grow stronger and put on weight (which they do comparatively rapidly). The closer your baby is born to their 'due date', the more likely they will be well and healthy and not require medical assistance. Medical advances have now made it possible for babies born after 28 weeks and before 37 weeks to have an excellent chance of survival. However, very premature babies usually need access to specialised care and a fully equipped intensive care nursery to achieve this.

NOTE: This pregnancy time scale is marked 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 37 weeks pregnant, you are at the start of week 38. Bear in mind that these descriptions (especially weight and length estimates) are just a guide and your baby may not be at the exact described stage during each specified week. Every woman and her baby are different and the range of normal is variable.