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Pregnancy Week 5

Fetal Development at week 5

Your Baby

The baby now measures between 1.0-1.5mm from head to tail, tiny enough to rest on the point of a ballpoint pen.

The part of the embryo that will go on to form the brain and spinal cord (the ‘primitive streak’) has appeared. It is now possible to identify the head and tail sections of your baby’s body – it looks a little bit like a tadpole!

The implanted embryo can be now be detected by ultrasound, although typically one isn’t conducted until around week 12.

The genetic blueprint in each cell tells the cell what to do and orders its migration to the spot in the baby’s body where the development will take place, but most developmental processes depend on a precisely coordinated interaction of genetic and environmental factors (like nutrition and the mother’s habits).

The fold of tissue that will form the baby’s head can now be identified. Because the central part of the embryo grows more rapidly than the peripheral part, it begins to fold inward to create your baby’s central nervous system.


The quality of your diet is especially important now, since the next 40 days mark a critical period in the development of your baby’s brain and spinal cord. Low-calorie or low-carbohydrate dieting even for short periods during pregnancy can reduce the amount of glucose available, which the baby’s brain needs for development.

Most changes that accompany pregnancy are normal, and although they may be uncomfortable, they are no cause for alarm. However, some symptoms need to be reported as soon as they occur so your practitioner can determine their importance. Be sure to contact your doctor if you experience vaginal bleeding, menstrual-like cramps, or lower abdominal pain.

Things to do when five weeks pregnant

  • You are likely to experience more pregnancy symptoms, including morning sickness, sore breasts, fatigue and frequent urination. Learn how to cope with morning sickness
  • Find out more about nutrition during pregnancy, and adjust your diet if necessary to make sure baby gets the nutrients it needs.
  • Consider when you’d like to tell family and friends that you’re pregnant. Many choose to reveal this at around 12 weeks, after the first scan, as pregnancy is considered relatively ‘safe’ from this point onwards.