Fetal Development Series: Part III

August 4, 2025

Recap & Welcome

Welcome back to the Fetal Development Series! This week we’ll be digging into Month 3, or the end of Trimester 1. As a recap, here’s some of the developments we’ve discussed already in your fetus’s body and in your own body:

• The very first developments in your embryo’s world, such as the amniotic sac, placenta, and umbilical cord, and the roles those organs play in bringing life to your embryo
• Further developments of major organ systems, such lungs, brain, spinal cord, heart, ears, and limbs of the embryo
• Psychological changes, such as mood swings, foggy-headedness, irritability, and forgetfulness
• Physical changes, such as GI problems (like constipation), frequent urination, shinier skin and hair, among many other possible symptoms
• The importance of prenatal checkups and what happens during them

Name Change & The Bump

So what’s in store for the very last month of the first trimester, and how will life change as you progress into the second trimester?

To start off, it’s important to remember that feeling anxious during this stage (and the whole way through, for that matter) is normal. After all, this first trimester is a very crucial time in the development of a child (The First Trimester 2019). Not that Trimester 2 and 3 aren’t important, but those first three months are the foundation for how the rest of the pregnancy will go. Breathe deep—you got this.

Now is the time that your embryo becomes a fetus (since we’ve passed the 8-week point and are now progressing through to week 13) (First Trimester 2022).

The most obvious sign of pregnancy—a baby bump—will still be elusive in this stage, but this is the time that you likely will start thinking about it the most, so we’re going to take some time talking about it here. During this time, your uterus continues to expand and is now above your pelvis (Herráiz). You will gain weight in increments now that your child’s growth is gearing up, so expect that bump to start making an appearance during the second trimester. With that being said, while most pregnant women will eventually have somewhat of a bump, the size and time of appearance will differ. 

If you’ve had children before, you’ll likely start showing sooner since your uterus and stomach muscles have expanded prior to this pregnancy (Higuera 2020). Your height and weight also matter: shorter women tend to show sooner than tall women and women who are thinner tend to show more than overweight women. The number of fetuses you’re carrying also counts; if you have twins or even triplets, you’ll likely show sooner than if only one fetus is present (Higuera 2020). Waist size matters as well, as women who have more petite waists will show a bump sooner than women who have wider waists (Higuera 2020). Getting an incorrect due date (i.e, you’re actually farther along in your pregnancy than you thought) or even abdominal bloating (due to retained fluid, which can be helped by drinking enough water, eating more fiber and less sugar) can affect when your bump shows (Higuera 2020). Even the size of the fetus (like having a smaller fetus rather than a larger one) can come into play.

As you can see, the question of “When will I show?” is more subjective than you may have thought since it depends on a diverse array of factors. But one thing is for certain: your pants are going to get tighter by the day!

Continued Symptoms

As for other symptoms, you can expect that some or all of the symptoms discussed in Part 2 of this series will still apply. This includes:

• Nausea and vomiting
• Sore breasts
• More noticeable veins
• White vaginal discharge
• Food cravings
• Fatigue
• Mood swings
• Constipation
• Bloating
• Heartburn
• Frequent urination
• Darkening of your areolas, vulva, and face
• Stronger sense of smell
• Thicker and shinier hair

But—and this is the happy part—the most common symptoms, or nausea and vomiting, usually eases up after this month. If not, than it would be wise to discuss any morning sickness concerns with a doctor. Since your blood flow has increased to supply blood to your womb, symptoms such as noticeable veins and mood instability (because of the increase in progesterone and estrogen) may arise (Week 9, 2023). 

Many women describe this stage of pregnancy as an emotional rollercoaster, so don’t be afraid to rest up and ask for help if you simply feel too worn out to take care of things (Week 9, 2023). Month 3 is the most hormonal and tiresome stage of pregnancy, so don’t push yourself more than you should. Since your body is working overtime to adjust to all the new physical changes, you may sleep longer at night and take naps during the day and still feel fatigued (FamilyDoctor.org Editorial Staff). Although this stage is tough, these feelings are normal and you should feel some energy return once the second trimester starts. 

Other symptoms that will likely persist are increased pigmentation, mood swings, frequent urination, GI upset, and hypersalivation (Herráiz). GI upset usually occurs in the form of acid reflux (heartburn) and constipation because of slowed muscular contractions in your intestines due to increased levels of progesterone (The First Trimester 2019). You could also have light cramping (like with menstrual pains), a metallic taste in your mouth, and light spotting (Week 8, 2023). If you find yourself needing to pee a lot at night, try to drink plenty of water during the day but ease up on consumption of liquids in the evening (Week 8, 2023). Belching and flatulence can also occur because of bloating (Week 10, 2023). 

Alongside cramping, you could also feel discomfort in your stomach area as your body stretches to make room for the fetus (Week 12, 2023). Dizziness, lightheadedness, or mild shortness of breath may occur because of all the extra blood being produced (FamilyDoctor.org Editorial Staff). Since your body is pumping around 50% more blood than usual, you could feel warm and sweaty alongside any dizziness (Week 11, 2023). Acne can also occur because of more oil in your skin (which also causes the infamous “glow”) (FamilyDoctor.org Editorial Staff).

Another important facet of the first trimester is that you don’t have to worry about eating for two (or more) yet; continue on with a good pregnancy diet for one (Week 12, 2023). It’s only in later stages of pregnancy when the baby is larger that you’ll need extra calories in your diet. 

Continued Fetal Development

Now that we talked about your own bodily changes, what’s happening in babyland? One important aspect of this stage of pregnancy is that your fetus is growing very quickly. The placenta, as we’ve discussed in previous posts, is still providing oxygen and nutrients to the fetus, as well as removing waste; it’s also in the process of growing small branches that are attaching itself to the inside of your womb (Week 8, 2023). 

What began in Month 2 (or the forming of major organ systems) is continuing its journey. These major organs are growing ever bigger and more complex by the day. The fetus’s head still looks larger than the rest of its body, but no longer looks extremely alien-ish because of increased detail in the facial area, such as eyelids and a mouth (Week 9, 2023). Your fetus even has a tongue with super tiny taste buds (Week 9, 2023). By week 10, ears are forming and their nose has two distinct nostrils (Week 10, 2023). Finger and toe separation happens later towards the end of the first trimester (Week 11, 2023). By the very end of  Week 12, your fetus will also have finger and toe nails and their larynx (voice box) will begin forming (The First Trimester 2019). 

A fetus’s genitalia will finish forming around weeks 11-12, but will not be able to be seen by an ultrasound scan yet, which usually happens within the next month or two (sorry, you have to wait a little longer for that gender reveal) (The First Trimester 2019). The fetus can move its arms and legs, although you likely will not feel movement this early (Week 11, 2023). Finally, your fetus’s heart rate zooms by at around 110 to 170 bpm (beats per minute), depending upon which week you’re in (Jones 2024). Many healthcare providers begin checking for a heartbeat around 10-12 weeks, so that’s something you have to look forward to as the end of this first tough trimester comes to a close (Jones 2024)!

Conclusion

The conclusion here is that the first trimester of pregnancy is no joke. But the good thing is that conditions should improve once the second trimester kicks in, which is coming very soon. Here’s a recap of the major features of your fetus’s development:

• Continued growth of major organ systems
• Finished formation of genitalia
• More facial features

And of course, here’s a recap of the laundry list of symptoms you may experience during this time:

• Nausea and vomiting
• Sore breasts
• More noticeable veins
• White vaginal discharge
• Food cravings
• Fatigue
• Mood swings
• Constipation
• Bloating
• Belching and flatulence
• Heartburn
• Frequent urination
• Darkening of your areolas, vulva, and face
• Stronger sense of smell
• Thicker and shinier hair
• Metallic taste
• Dizziness or lightheadedness
• Sweaty and/or warm
• Acne
• Increased oil production/glow
• Fatigue and tiredness

Finally, here’s a few aspects of this stage of pregnancy you have to look forward to:

• The onslaught of possible symptoms should ease up soon
• Heartbeat check time!
• Gender reveal is on its way

Hopefully the first part of this series helped you learn more about yourself and your growing fetus. Stick around for the first post of Trimester 2!

Citations

“First Trimester.” Cleveland Clinic, 22 Aug. 2022, my.clevelandclinic.org/health/articles/9699-first-trimester.

FamilyDoctor.org Editorial Staff. “Changes in Your Body during Pregnancy: First Trimester.” FamilyDoctor.org, Aug. 2024, familydoctor.org/changes-in-your-body-during-pregnancy-first-trimester/.

Herráiz, Miguel Ángel. “Changes in the third month of pregnancy.” Natalben, www.natalben.com/en/pregnancy-months/2-months-pregnant.

Higuera, Valencia. “When Does Your Baby Bump Start to Show?” Healthline, medically reviewed by Carolyn Kay, 13 Jan. 2020, www.healthline.com/health/pregnancy/when-do-you-start-to-show.

Jones, Brandi. “What Is a Normal Fetal Heart Rate During Pregnancy?” Verywell Health, medically reviewed by Renita White, 5 Dec. 2024, www.verywellhealth.com/normal-fetal-heart-rate-5216868.

The First Trimester. “Wellness and Prevention.” John Hopkins Medicine, 2019, www.hopkinsmedicine.org/health/wellness-and-prevention/the-first-trimester.

Week 8. Start for Life, NHS, 13 June 2023, www.nhs.uk/start-for-life/pregnancy/week-by-week-guide-to-pregnancy/1st-trimester/week-12/.

Week 9. Start for Life, NHS, 13 June 2023, www.nhs.uk/start-for-life/pregnancy/week-by-week-guide-to-pregnancy/1st-trimester/week-12/.

Week 10. Start for Life, NHS, 13 June 2023, www.nhs.uk/start-for-life/pregnancy/week-by-week-guide-to-pregnancy/1st-trimester/week-12/.

Week 11. Start for Life, NHS, 13 June 2023, www.nhs.uk/start-for-life/pregnancy/week-by-week-guide-to-pregnancy/1st-trimester/week-11/.

Week 12. Start for Life, NHS, 13 June 2023, www.nhs.uk/start-for-life/pregnancy/week-by-week-guide-to-pregnancy/1st-trimester/week-12/.

About the Author
Krista Ruffo, born, raised, and still living in Orlando, Florida, began blogging with South Project in February of 2025. She’s a UCF alum with a BA in English and a Certificate in Editing and Publishing. A passionate writer and reader, Krista aspires to work in book publishing in the future. She currently works as a Content Coordinator for a family magazine. In her free time, she enjoys writing poems, taking photos, making art, hiking, and gardening.