Pregnancy & Development

You missed your period. Now what?

hCG - human chorionic gonadotropin; AKA - the "pregnancy hormone" hCG is produced by the embryo shortly after it implants into the uterus. At around 12 weeks of pregnancy, the placenta will be fully formed and will take over hCG production.

What is a pregnancy test actually detecting?

It's time to take a pregnancy test!

Congratulations!

• We'll be following the class pregnancy and development of our embryo/fetus throughout the entire reproductive system unit.
• At the start of each class, we'll discuss what's happening with the pregnancy person as well as the developing embryo/fetus starting with month 1 all the way up until you deliver!

What to expect when you're expecting: A month-by-month guide to pregnancy & fetal development

Month 1: Weeks 1-4 Embryonic Development

Weeks 1 & 2: no baby at all! WHAT?!? Week 3 & 4: Fertilization & Implantation

• zygote -> morula -> blastocyst
• Inner cells will become embryo
• Outer cells will become placenta

Month 1: Weeks 1-4 Pregnancy Developments

Week 1: menses Week 2: ovulation around day 14 Week 3 & 4: Fertilization & Implantation

• May have some implantation bleeding
• Should have a + home pregnancy test by the end of week 4 (up to 5 days before missed period)

Month 2: Weeks 5-8 Embryonic Development

• 3 tissue layers -> ectoderm, mesoderm, endoderm
• Neural tube closes -> folic acid required
• Early facial features develop
• Limbs begin developing
• Umbilical cord development
• Week 6 -> detect heartbeat via ultrasound
• Week 8 -> now called a fetus

• Hormone levels increase (hCG, estrogen, progesterone, and relaxin)
• Signs & symptoms increase (nausea, breast tenderness, fatigue, heartburn)
• Blood volume increases
• Routine testing begins (CBC, Blood type & Rh factor, Antibody screen, urinalysis, STIs, Hep B & C, rubella immunity)
• May get serial quantitative hCG draws

Month 2: Weeks 5-8 Pregnancy Development

• By the end of month 3, fetus is fully formed
• Circulatory and urinary systems begin functioning
• Reproductive organs have developed, but are difficult to distinguish via ultrasound
• Teeth forming under gums
• Fingernails & toenails developing

Month 3: Weeks 9-12 Fetal Development

Month 3: Weeks 9-12 Pregnancy Development

• Will likely have first ultrasound
• Nuchal translucency & nasal bridge

• Can hear heartbeat through fetal doppler over pelvic region
• NIPT

• Risk of spontaneous abortion decreases significantly
• Placenta is fully formed by about 12 weeks and produces
• hCG, estrogen, & progesterone

Month 4: Weeks 13-16 Fetal Development

• Fingers & toes well developed
• Eyelids, eyebrows, eyelashes, nails, & hair fully formed
• Teeth and bones become denser
• Fetus sucks thumb, stretches, and yawns
• Genitalia can typically be visualized in ultrasound

Month 4: Weeks 13-16 Pregnancy Development

• This is the start of the 2nd trimester
• Nausea, vomiting, and fatigue usually decreases
• Heartburn and digestive issues usually increase
• Breast changes
• Bleeding gums

• Baby is covered in lanugo & vernix
• Muscles are developing and baby is exercising them
• Week 20 -> anatomy scan

Month 5: Weeks 17-20 Fetal Development

Month 5: Weeks 17-20 Pregnancy Development

• Can feel "quickening"
• Typical signs and symptoms continue, but probably are not significantly worsening
• 20 weeks -> begin fundal height measurements

• Fetus's skin is translucent red, wrinkled, and has visible veins
• Finger and toe prints are developed
• Will often start having hiccups
• Week 23 -> early viability

Month 6: Weeks 21-24 Fetal Development

• Colostrum development
• Braxton-Hicks contractions

Month 6: Weeks 21-24 Pregnancy Development

• Fetus is developing and reserving body fat
• Hearing fully developed
• Responds to stimuli (light, sound, movement, etc)

Month 7: Weeks 25-28 Fetal Development

• Back pain worsens
• Prior pregnancy symptoms continue
• Gestational diabetes screen
• If you have a negative blood type, you need a RhoGAM shot
• Week 28 -> start the 3rd trimester!

Month 7: Weeks 25-28 Pregnancy Development

• Continue increasing fat
• Rapid brain development
• Most internal organs are well developed - lungs still immature
• Lanugo starts falling off
• Testes begin descending into scrotum

Month 8: Weeks 29-32 Fetal Development

• Shortness of breath increases
• Fatigue increases
• Varicose veins & hemorrhoids may develop
• Urinary frequency, urgency, &

incontinence may develop

• Your hair is probably looking great!

Month 8: Weeks 29-32 Pregnancy Development

• Reflexes and movements are much more coordinated
• Continues to grow in size
• Lungs continue to mature

Month 9: Weeks 33-36 Fetal Development

• Fetus may begin to "drop" into pelvis -> relieves some symptoms
• Pelvic pressure increases
• Stretch marks are probably developing

Month 9: Weeks 33-36 Pregnancy Development

• Firm grasp
• Vernix and lanugo have decreased/may be gone
• Fetus will finalize it's position -> ideally head down & spine anterior
• 37 weeks -> early term
• 39-40 weeks -> full term
• 41-42 weeks -> late term

Month 10: Weeks 37-42 Fetal Development

• Increased pelvic pressure
• Cervix may begin to dilate and efface
• 37 weeks -> Group B Strep swab
• 40 weeks and onward -> BPP & NST

Month 10: Weeks 37-42 Pregnancy Development

Around 40 weeks, the hypothalamus will create oxytocin and the posterior pituitary will release it. Oxytocin targets the muscular middle layer of the uterus (myometrium) to stimulate contractions. This is an example of a postive feedback mechanism.

Time for Delivery!

To simplify things, doctors traditionally start counting the weeks of pregnancy (on average, there's 40) with the first day of your last period BEFORE you got pregnant. This is because most people do not know the exact date that they ovulated and then conceived. However, most females do track their periods and can report a pretty accurate date.

Weeks 1 & 2

Yep, you're not actually pregnant

Nuchal translucency - a measurement of the amount of fluid behind the neck. A measurement that is abnormally large could indicate birth defects, particularly Down's Syndrome. Nasal bridge - the bridge of the nose is also viewed and measured. If it does not appear to be developing correctly,this could indicate Down's syndrome

Group B strep

Bacteria that normally lives in vagina and digestive tract and does not typically cause issues. When baby is born vaginally, if it comes into contact with GBS (in eyes, nose, mouth), it can lead to a severe and potentially deadly form of meningitis. GBS+ individuals should get IV antibiotics during delivery to prevent transmission. A c-section is not needed for GBS.

a temporary organ that forms in the uterus during pregnancy and connects the developing baby to the mother. Functions:

Placenta

• nutrient and gas exchange
• hormone production - produces hCG, estrogen, and progesterone - all will help prevent menstruation and get the uterus ready for delivery

Gestational Diabetes Screen

Gestational diabetes - diabetes during pregnancy - caused by the placenta affecting your ability to use insulin correctly. Blood is drawn to get a baseline measurement, then pregnant person drinks a drink with a large amoutn of glucose. Blood drawn 1 hour later to make sure your blood glucose was well controlled by your body. If you have gestational diabetes, your baby will also create excess insulin. This could lead to a large baby and cause seizures after birth

Neural Tube

a narrow channel that develops in the embryo during the third and fourth weeks of pregnancy and forms the brain and spinal cord

Fundal Height

a measurement of the distance from the top of the uterus to the top of the pubic bone. This is used to make sure the fetus is growing at an appropriate rate. With a singleton (1 fetus) pregnancy, the fundal height should match in cm what you are in weeks pregant. E.g. if yuo are 24 weeks pregnant, fundal height should be about 24 cm

Dilation and effacement

Cervical dilation - opening of cervix enlarges; considered "fully dilated" at 10 cm Cervical effacement - cervix thins

Fetal Doppler

handheld ultrasound device that can be used to detect the fetal heart rate

BPP & NST

BPP = biophysical profile - in depth ultrasound that makes sure that amniotic fluid levels are normal and that the fetus is moving, has a good heart rate and respiratory rate. Also checks blood flow to uterus and umbilical cord. NST = non-stress test - sensors are placed on abdomen to check for uteririne contractions.

Varicose Veins & Hemorrhoids

Varicose veins - wollen, twisted veins that appear just under the skin, usually in the legs. They are common in pregnancy because of the increased blood volume and weight/pressure Hemorrhoids are varicose veins in and around the rectum.

Embryonic Tissue Layers

Ectoderm - outer layer; will become the skin and nervous tissue Mesoderm - inner layer; will become muscle tissue, bones, heart, blood vessels, genitals, and urinary system Endoderm - inner layer - will become digestive organs, liver, pancreas, lungs, and thyroid

Anatomy scan

Routine ultrasound. Ultrasound tech will perform an in-depth scan of the baby's internal organs, brain, and bones. They will also scan the placenta and umbilical cord to make sure that blood flow is good.

Umbilical Cord

a tube-like structure that connects a fetus to the placenta and provides the fetus with oxygen, nutrients, and a way to remove waste.