Your Baby at 33 Weeks

A Closer Look at Week 33

Week 33 is a crucial period for your baby's immune system development. Antibodies — specifically immunoglobulin G (IgG) — are being actively transferred across the placenta from your bloodstream to your baby's. These maternal antibodies will provide passive immunity for the first few months of life, protecting your newborn against infections while their own immune system matures. This transfer intensifies as the due date approaches, which is one of the reasons why preterm babies are more vulnerable to infection.

The bones of the skull remain deliberately unfused, connected by flexible membranes called fontanelles (commonly known as 'soft spots'). This design allows the skull to compress and mould during passage through the birth canal, then gradually expand as the brain grows during infancy. The anterior fontanelle (the larger soft spot on top of the head) typically closes between 12 and 18 months after birth, while the posterior fontanelle closes within a few months.

You may find that you overheat easily during this stage of pregnancy. Your metabolic rate has increased significantly to support the demands of a growing baby, and this generates extra body heat. Combined with the insulating effect of increased body fat and the extra blood volume circulating through your system, even mild exertion can leave you feeling flushed and sweaty. Wearing breathable, layered clothing, staying in well-ventilated spaces, and drinking plenty of cold water can help manage this.

This is also a good week to discuss your birth preferences with your partner and healthcare provider if you haven't already. Topics to consider include pain management preferences (natural, epidural, or combined approaches), who you want in the delivery room, cord blood banking, skin-to-skin contact immediately after birth, and delayed cord clamping.