Pregnancy week 5 - baby's development and your body
The information in this article is intended for general information only and does not replace medical advice. Always contact your midwife or maternity care provider if you are concerned about your or your baby’s health.
Are you in week 5 of your pregnancy? Learn all about how the embryo develops this week, changes in your body, and early pregnancy symptoms.
Week 5 is the third week after fertilization.
By this time, the fertilized egg has attached itself to the uterine lining, and the embryo is developing rapidly. It now consists of three cell layers that will form different parts of your baby's body.
Size:
The embryo is about 0.2–0.4 cm or 0.079–0.157 inches in size, from head to rump.
Weight:
Less than 1 gram or 0.035 ounces.
Embryo development:
The embryo is developing quickly, and the cells continue to divide and differentiate. The embryo now consists of three cell layers.
The outermost layer will become your baby's outer skin layer, central and peripheral nervous systems, eyes, and the inner parts of the ears.
The middle layer of cells will develop into the baby's heart, circulatory system, bones, ligaments, kidneys, and large parts of the reproductive system.
The innermost layer of cells will become the baby's lungs and intestines.
Your body:
By now, your period would have come if you weren't pregnant, depending on how long your menstrual cycle usually is.
You can now get a clear result with most pregnancy tests.
During this week, you may also begin to notice early pregnancy symptoms, such as fatigue, tender breasts, or mild nausea.
1. 1177 Vårrdguiden (Sweden's national online healthcare portal). “Pregnancy week by week”, https://www.1177.se/barn--gravid/graviditet/om-graviditeten/graviditeten-vecka-for-vecka/
2. Cleveland Clinic. Fetal development: Stages of growth, https://my.clevelandclinic.org/health/articles/7247-fetal-development-stages-of-growth
3. Mayo Clinic. Prenatal care: Healthy pregnancy week by week, https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/prenatal-care/art-20045302