Baby's Development in Month 3 of Pregnancy | Growth in the Embryonic and Fetal Stages

📱The Maila Maternity Health Tracker app is now available for iOS! Install the app for weekly videos and articles: https://tinyurl.com/Maila-Maternity-iOS

______
The third month of pregnancy covers weeks 9 to 13. Details of the baby's growth and development during each of these weeks appear below.

Week 9
At nine weeks, the embryo starts to appear more distinctly human. Its caudal eminence (embryonic tail) begins disappearing, and its facial features continue developing [1]. The fingers and toes are clearly separated digits [2].

The digestive system has formed and continues to grow, specifically the intestines, pancreas, bile ducts, gallbladder, and anus [1]. The embryo begins developing nipples and hair follicles, too [1].

Sexual differentiation starts with the internal reproductive organs, including the embryo’s ovaries or testes [1]. While one can distinguish the embryo’s sex genetically, the external genitals of female and male embryos are structurally identical at this point [1,3].

Week 10
At ten weeks, the embryo’s brain grows and expands as it produces 250,000 new neurons each minute [1]. The embryo’s head, which now contains the major brain structures, is almost as large as the rest of the embryo’s body [4].

Through ossification, bone starts replacing skeletal cartilage [4]. Ossification begins in the femoral bones (long thigh bones) [2]. Teeth buds appear [1].

As the kidneys start working, the amniotic fluid now includes fetal urine [4]. The external genitals of female and male embryos are forming but remain structurally identical [4]. Male embryos start producing testosterone [1].

This week marks the last of the embryonic phase. The rudimentary structures and functions of the embryo’s organ systems will finish their initial development [3,4].

Week 11
At 11 weeks, the baby is considered a fetus rather than an embryo [2,4]. Now that the early embryonic organ systems have developed, they will continue to grow and differentiate during the fetal period [3].

Red blood cells begin forming in the liver [2]. Sexual differentiation and ossification (the process of bone development) are ongoing [1,3]. The fetus’s eyelids begin fusing shut [3].

The ears appear lower on the fetus’s head and gradually move upwards throughout pregnancy [2]. The fetus makes poorly controlled and jerky movements [3]. It swallows amniotic fluid, which now includes fetal urine [3].

Week 12
At 12 weeks, the fetus’s brain continues to grow and expand [3]. Its eyes are widely separated, and its body is elongating [2]. As the limbs lengthen, they will gradually become more proportional to the fetus’s body [2].

Fingernails start developing, and the external genitalia continue to form male or female characteristics [2]. The fetus’s intestines are still in the umbilical cord but will soon relocate to the abdomen [2].

The fetus swallows amniotic fluid, including urine. However, fetal waste products exit the amniotic fluid by passing across the placental membrane, where the maternal circulatory system removes them [2].

The end of 12 weeks coincides with the end of the first trimester [1].

Week 13
At 13 weeks, the fetus’s intestines now grow within the abdomen rather than the umbilical cord [2]. The active fetus still moves uncontrollably, though it may be able to put its thumb into its mouth [1].

The fused eyelids protect the fetus’s developing eyes, which are moving closer together [1,3]. The ears start moving upward and lie flatter against the head [3]. The limbs continue to lengthen, becoming more proportional to the fetus’s body [2].

The external genitalia continue to form male or female characteristics but remain immature [2]. The liver will keep producing red blood cells until this process begins in the spleen [2].

______
At Maila Health, we’re on a mission to improve maternal and newborn health outcomes and experiences through meaningful innovation in digital health. If you’re pregnant or postpartum, we’re here to help.

● Learn more about Maila Health: https://mailahealth.com/
● To hear more from us, subscribe to our YouTube channel!

#FirstTrimester #PregnancyJourney #Fetus #PregnancyMonthByMonth #MailaHealth

______
References:
1. Harms R, Wick M, editors. Mayo Clinic Guide to a Healthy Pregnancy. Boston: Da Capo Press; 2011.
2. Moore KL, Persaud TVN, Torchia MG. The Developing Human: Clinically Oriented Embryology. Philadelphia: Elsevier; 2016.
3. Betts JG, Young KA, Wise JA, Johnson E, Poe B, Kruse DH, et al. 28.3 Fetal Development. Anatomy & Physiology. Houston: OpenStax; 2013.
4. Betts JG, Young KA, Wise JA, Johnson E, Poe B, Kruse DH, et al. 28.2 Embryonic Development. Anatomy & Physiology. Houston: OpenStax; 2013.

______
Produced and written by: Samantha Lattof, PhD MSc
Medically reviewed by: Ayodeji Olelakan Abere, MD MBA MHA
Animation by: SciePro / Pond5
Music from: Envato Elements
Narration by: Ava / Wellsaid