Week 5
Your baby is the size of a Sesame seed
Baby Size
Sesame seed
Length
0.12 in (3 mm)
Weight
Less than 0.04 oz
Trimester
First Trimester
Your Baby at Week 5
At week 5, your baby is about the size of a sesame seed but growing rapidly. The heart is now beating in a regular rhythm.
Key milestone: The brain, spinal cord, and heart continue rapid development. Arm and leg buds appear.
Your Symptoms
Morning sickness may start. Fatigue, frequent urination, food aversions.
Tip for This Week
Eat small, frequent meals to manage nausea. Ginger tea or crackers before getting out of bed can help.
Your Body at Week 5
During the first trimester, your body is working overtime to build the placenta and support rapid embryonic development. Hormones like hCG, estrogen, and progesterone surge, causing many of the symptoms you're experiencing. Your blood volume is already increasing, and your uterus is beginning to expand — even if you can't see it yet.
Your baby at week 5 is the size of a Sesame seed, measuring about 0.12 in (3 mm) and weighing roughly Less than 0.04 oz. The focus is on forming all major organ systems that will sustain your baby through the rest of pregnancy and beyond.
Your Baby's Development This Week
At week 5, your baby is about the size of a sesame seed but growing rapidly. The heart is now beating in a regular rhythm. The key milestone this week is that the brain, spinal cord, and heart continue rapid development. arm and leg buds appear.
The first trimester is a period of incredible transformation. From a single cell to a fully formed fetus in just 12 weeks — your baby's development is happening at an astonishing pace. Each week brings new organs, new abilities, and new reasons to marvel at the process.
This week's voice theme
“Little limbs, big dreams — growing strong.”
Imagine hearing this every morning — a voice note from your baby that evolves week by week.
Hear your baby's voice →Frequently Asked Questions
When does morning sickness start?
Morning sickness typically begins around week 5-6 of pregnancy, though it can start earlier or later for some women.
What does a 5-week ultrasound show?
At 5 weeks, an ultrasound may show the gestational sac and possibly the yolk sac. The fetal pole may be barely visible.