5th week: The missed period
- Weeks and days
- 4+0 to 4+6
- Month
- 2
- Trimester
- 1
This week, your period does not come, and a pregnancy test is usually positive. The embryo grows from 0.2 to about 2.5 millimeters, and the neural folds and the beginnings of the heart form. On ultrasound, the gestational sac can be seen from about 4+4.
Week 5 of 40
Calculate your weekHow big is the embryo?
0.2 to 2.5 mm
The embryo forms three germ layers, from which all organs develop. In addition, the neural folds form as the precursor of the neural tube, and toward the end of the week the beginnings of the heart.
Length according to the Carnegie stages of embryology.
This week
Your baby
- Three germ layers form, and all organs develop from them.
- The neural folds take shape; the neural tube is still open.
- The beginnings of the heart form at around 4+5 to 5+0; the heart is not beating yet.
Your body
- With a 28-day cycle, your period is due on 4+0. One week later, a test detects 97% of pregnancies.
- The median hCG level is 141 mIU/ml; 9.5 to 750 is normal. More in the hCG levels chart.
- In two thirds of women, nausea already begins 11 to 20 days after ovulation, that is, by the end of this week at the latest.
What matters now
- Folic acid 400 µg daily. According to the German recommendation, 800 µg if you did not already start taking it 4 weeks before conception.
- Iodine 100 to 150 µg daily.
- Make an appointment with your gynecologist. After IVF, the blood test at the fertility clinic usually follows now.
Get checked right away: one-sided pain in the lower abdomen, heavy bleeding, pain in the tip of the shoulder, or dizziness. This can be a sign of an ectopic pregnancy.
On ultrasound
- 4+4
Gestational sac was visible in all pregnant women from this point.
- 5+1 to 5+5
Yolk sac only follows in the 6th week of pregnancy.
The embryo and heartbeat are not yet expected this week. In Germany, health insurance pays for an early ultrasound only if a disrupted early pregnancy is suspected.
Frequently asked questions about the 5th week of pregnancy
How big is the baby in the 5th week of pregnancy?
The embryo grows from 0.2 to about 2.5 mm. In the middle of the week, it is about the size of a poppy seed at 1.2 mm.
Can you see the heartbeat in the 5th week of pregnancy?
No. The heart only starts to beat at around 5+1, and in one study, the heartbeat was visible on ultrasound in all women from 5+6.
I haven’t taken any folic acid yet. What now?
Start right away. According to the German recommendation, you then take 800 µg daily until the end of the 12th week of pregnancy, because the neural tube closes in the next few days.
Which month is the 5th week of pregnancy?
The 2nd month of pregnancy, in the 1st trimester. Figures such as 4+3 weeks also belong to the 5th week of pregnancy.
Sources
- Carnegie stage table, UNSW Embryology
- Wilcox AJ et al.: Natural limits of pregnancy testing in relation to the expected menstrual period, JAMA 2001;286:1759
- Gadsby R et al.: The onset of nausea and vomiting of pregnancy, BMC Pregnancy Childbirth 2021;21:10
- Bree RL et al.: Transvaginal sonography in the evaluation of normal early pregnancy, AJR 1989;153:75
- Beta-HCG, test directory with the table from the Roche Elecsys HCG+β package insert, Ulm University Hospital (Universitätsklinikum Ulm), as of 8 July 2020
- Alaze-Hagemann F et al.: Recommendations by the Healthy Start Network 2026 (Handlungsempfehlungen Netzwerk Gesund ins Leben), Geburtshilfe Frauenheilkd 2026;86(6):e60
- Maternity guidelines (Mutterschafts-Richtlinien), Federal Joint Committee (Gemeinsamer Bundesausschuss), in effect since 25 August 2026
- Weeks 5 to 8 of pregnancy, familienplanung.de, Federal Institute for Public Health (BIÖG), as of 13 June 2024
- Ectopic pregnancy, NHS, as of 19 August 2026