Describe stages of development from fertilisation to end of gestation

Qualification: NCFE CACHE Level 3 Diploma for the Early Years Educator
Unit: Unit 1.6: Understand the needs of the mother and baby during pre-conception, pregnancy and the first year of life
Learning outcome: Understand development from conception to end of gestation
Assessment criteria: Describe stages of development from fertilisation to end of gestation


This page describes the stages of development of a baby from fertilisation to the end of gestation.

Fertilisation is when the sperm meets the egg, and they join together. This is also known as conception.


Gestation is the period of time from fertilisation to birth and can be divided into three stages; germinal, embryonic and fetal.

Germinal stage (0-2 weeks)

After fertilisation, the zygote (fertilised egg) undergoes a series of cell divisions to form a ball of cells called the blastocyst. The blastocyst implants itself onto the lining of the uterus (womb), where it will continue to grow and develop over the next nine months.


Embryonic stage (3-8 weeks)

The baby’s major organs and body systems begin to develop during the embryonic stage. The heart starts to beat, and the nervous system begins to form.

Fetal stage (9-40 weeks)

During the fetal stage, the baby continues to grow and develop. The organs and systems that were started during the embryonic stage continue to develop and mature.



Pregnancy usually lasts around 40 weeks, split into three trimesters.

During the first trimester (weeks 1-12), the baby’s body begins to form, and the heart, brain and nervous system start to develop.


The second trimester (weeks 13-27) is a time of rapid growth. The baby starts to move, and the mother will feel her first kick around week 22.

The third trimester (weeks 28-40) is a time of final development and growth. The baby’s organs are fully developed, but the lungs are not yet mature. Around week 37, the baby is considered full-term and ready for birth.

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