• 4-weeks-pregnancy-couscous

    At 4 weeks, right after implantation, the baby is the size of a tiny grain of Couscous. Uncooked. Length: 0.04 inches (1 mm), Weight: <0.04 oz (<1 gram)

  • 5 Week pregnancy size pumpkin seed5 Weeks of pregnancy: Pumpkin seed

    At 5 weeks of the pregnancy, the baby is the size of a pumpkin seed. Length: 0.06 inches (1 mm), Weight: <0.04 oz (<1 gram)

  • Slideshow Image6 weeks of pregnancy: Large pea

    At 6 weeks of the pregnancy, the baby is about the size of a large pea. Length: 0.1 inches (3 mm), Weight: <0.4 oz (<2-3 gram)

  • 11 weeks pregnancy iwatch11 weeks of pregnancy: An Apple Watch

    At 11 weeks of the pregnancy, the baby is about the size of an Apple Watch. Average length: 1.6 inches (40 mm), Average weight: 0.25 oz (7 gram)

  • 14-weeks-pregnancy-sushi14 weeks of pregnancy: Sushi

    At 14 weeks of the pregnancy, the baby is about the size of an average piece of Sushi. Average length: 3.5 inches (85 mm), Average weight: <1.5 oz (45 gram)

  • 13-weeks-pregnant-medium-cookie13 weeks of pregnancy: A small cookie

    At 13 weeks of the pregnancy, the baby is about the size of small cookie. Average length: 2 inches (75 mm), Average weight: 1oz (23 gram).

  • 15-weeks-pregnancy-amazon-echo-dot15 weeks of pregnancy: An Amazon Echo Dot

    At 15 weeks of the pregnancy, the baby is about the size of an Echo Dot. Average length: 4 inches (100 mm), Average weight: 2.5 oz (70 gram)

  • 16-weeks-pregnant-kitten-cute16 weeks of pregnancy: A kitten at birth

    At 16 weeks of the pregnancy, the baby is about the size of a small kitten at birth. Average length: 4.5 inches (115 mm), Average weight: 3.5oz (100 gram).

  • 18 weeks pregnancy iphone18 weeks of pregnancy: An iPhone

    At 18 weeks of the pregnancy, the baby is about the size of an iPhone. Average length: 5.5 inches (140 mm), Average weight: <6.7 oz (200 gram)

  • 21-weeks-pregnancy-ipad21 weeks of pregnancy: An iPad

    At 21 weeks of the pregnancy, the baby is about the size of an iPad. Average length: 10.5 inches (270 mm), Average weight: 13 oz (350 gram)

  • 26-weeks-pregnancy-macintosh26 weeks of pregnancy: An old Apple Macintosh

    At 26 weeks of the pregnancy, the baby is about the size of an old Apple Macintosh. Average length: 14 inches (360 mm), Average weight: 1.6 lb (760 gram). The Macintosh weighed 16.6 lb but was also 14 inches high.

One of the most frequent question asked by women during pregnancy is how big the baby is and if it has grown normally. Many midwives and doctors compare the baby's size to fruit, vegetables, or other items to make it more clear to the woman exactly what size the baby is. 

One of the problems with estimating the baby's weight is that different countries, different populations, and even whether the baby is a boy or girl will make a difference in the baby's weight.

The fetus is usually measured until 20 weeks with the crown-rump-length, from top of the head to the butt. After that, it's measured head-to-heel.

In 2017 in PLOS a study was published showing the weight and measurements of a baby for 10 countries by weeks of the pregnancy (printable paper).

REFERENCES

  • Kiserud T. et al The World Health Organization Fetal Growth Charts: A Multinational Longitudinal Study of Ultrasound Biometric Measurements and Estimated Fetal Weight. PLOS 2017 https://www.ncbi.nlm.nih.gov/pubmed/28118360 . [Accessed April 2019
  • Doublet PM, et al. 1997. Improved birth weight table for neonates developed from gestations dated by early ultrasonography. Journal of Ultrasound Medicine 16(4):241-9. https://www.ncbi.nlm.nih.gov/pubmed/9315150 [Accessed April 2019
  • Hadlock FP, et al. 1992. Fetal crown rump length: Reevaluation of relation to menstrual age (5-18 weeks) with high resolution real-time US. Radiology 182(2):501-5. https://www.ncbi.nlm.nih.gov/pubmed/1732970  [Accessed April 2019
  • Usher R, et al. 1969. Intrauterine growth of live-born Caucasian infants at sea level: Standards obtained from measurements in 7 dimensions of infants born between 25 and 44 weeks of gestation. Pediatrics 74(6):901-10. https://www.ncbi.nlm.nih.gov/pubmed/5781799 [Accessed April 2019