Pregnancy Timeline by

Fertilization

sophiebarthel6 — 2024-10-17 17:11:15 UTC

The joining of the gametes (sperm and egg), it must occur within the first 24 hours of the egg being released and sperm must race to it (many do not survive). The acrosome uses enzymes to eat through the egg’s clear membrane and then releases its contents. The now fertilized ovum has 46 chromosomes (23 from each parent). The joined gametes are called a zygote.

Implantation

sophiebarthel6 — 2024-10-17 17:22:05 UTC

Once in the uterus, the morula develops into a blastocyst. This contains 2 types of cells, the trophoblast (outer layer that provides nutrients) and the inner cell mass (embryoplast, develops into actual embryo). Implantation occurs when the trophoblast dissolves some of the endometrium, allowing the blastocyst to sink into it (begins ~ day 7).

** implantation occurs in the second week (completes in 10-14 day mark)

Cleavage

georgiarfunk — 2024-10-17 17:27:23 UTC

The zygote begins to divide (one cell into two, two into four, etc) through the process of mitosis (the first 30 h). While the cells are dividing, the size of the zygote stays the same. The final grouping of sixteen cells is called a morula, and it reaches the uterus three to five days after fertilization.

Key hormones for continuing development

georgiarfunk — 2024-10-17 17:45:11 UTC

HcG is similar to the lutenizing hormone since it maintains the corpus luteum and allows continuing secretion of estrogen & progesterone. In the last four months, it’s production declines and the placenta can maintain E & P for the endometrium.

** the release of HcG is what prevents a women from getting her period (a clear sign of pregnancy)

Week 1 —>

sophiebarthel6 — 2024-10-17 17:45:31 UTC

Week one means you're ovulating, and the entire pregnancy process is about to begin.

When ovulation occurs, and depending on the sperm cells, the egg now travelling through the fallopian tubes & may become fertilized.

Week 2 —>

sophiebarthel6 — 2024-10-17 17:48:57 UTC

Morphogenesis and neurulation occurs

Weeks 3-8 —>

sophiebarthel6 — 2024-10-17 17:50:26 UTC

Important Events:

organ development, base functions start to occur, new name!

Gastrulation and morphogenesis

georgiarfunk — 2024-10-17 18:03:38 UTC

After implantation, the inner cells start to specialize. Gastrulation is the beginning of the cells devellopment. The embryo has three layers (endoderm, ectoderm, mesoderm) to form the embryonic disk in the blastocyst. The embryo is now a gastrula.

Teratogen: Nicotines effect in trimester one

georgiarfunk — 2024-10-18 01:06:10 UTC

Nicotine will have the greatest effect on fetal development within the first nine weeks post fertilization. If nicotine is in the mother’s blood stream, it can enter into the baby’s via the umbilical cord and cause health defects. These include constricted blood vessels resulting in a lack of oxygen, this can lead to and underweight or premature baby due to developmental issues. Furthermore, the lack of oxygen can even cause miscarriages and stillbirths.

Other things that could happen is a cleft palette, weakened placenta and ectopic pregnancy (in ovarian duct).

[https://www.betterhealth.vic.gov.au/health/healthyliving/pregnancy-and-smoking#]

Morphogenesis

georgiarfunk — 2024-10-18 16:53:09 UTC

A series of events to form distinct structures in the baby, it depends to the availability of embryonic cells to start to become different from each other.

Differentiation

georgiarfunk — 2024-10-18 17:00:56 UTC

The process that allows a cell to develop into a certain shape to perform specific functions. All of the cells, tissues and organs are derived from the germ layers in gastrulation to allow differentiation to occur.

Neurulation

georgiarfunk — 2024-10-20 01:59:18 UTC

One of the first things that develops to form the embryo’s human shape are the mesoderm cells that become a notochord. It is the base of the skeleton and the nervous system develops just above it through the ectoderm. When these fuse it develops into the brain and spinal cord, which is the start of organ formation.

** occurs in weeks two and three

Organ development

georgiarfunk — 2024-10-20 02:25:33 UTC

Embryonic structures —>

georgiarfunk — 2024-10-20 02:33:12 UTC

These are formed from the process of differentiation and are key to fetal growth and nutrition

Extra-embryonic membranes

georgiarfunk — 2024-10-20 03:01:05 UTC

While organs are developing, membranes outside the embryo form. These protect, provide nutrients, and help with respiration/excretion to the embryo. The membranes are called the allantois, amnion, chorion and yolk sac and some will develop into the placenta and umbilical cord.

Trimester one video

georgiarfunk — 2024-10-20 03:02:02 UTC

This video provides a basic summary of fetal development in the first three months of pregnancy. It overviews many points that were mentioned throughout the presentation.

Placenta

georgiarfunk — 2024-10-20 03:25:44 UTC

Near the end of week 2, the chorion has projections that go into the uterine lining, this is the start of the placenta. THe placenta is rich in blood vessels and metabolic exchanges happen through it. It transports/stores nutrients, transports out wastes and brings in oxygen through blood, secretes/absorbs hormones, and transports antibodies (passive immunity).

**oxygen/nutrients to diffuse, doesn’t filter out teratogens (ex. Nicotine or alcohol). Dangerous substances can pass from the mother to the baby.

Umbilical cord

georgiarfunk — 2024-10-20 03:40:46 UTC

Rope-shaped structure that goes from the naval area to the placenta . It takes oxygen depleted blood out of the fetus to the placenta and the vein brings oxygen rich blood to the fetus. It has twists because the vein is longer than the artery which is why some baby are born with it looped once around their neck (typically the doctor can slide it off).

**forms when the yolk-sac shrinks and amniotic sac gets bigger

Month 4

sophiebarthel6 — 2024-10-20 04:46:38 UTC

The fourth month of pregnancy consists of lots of physical growth. The fetus's face begins to look more like a human's, and joints begin to form. Skin will be a bright pink colour, as capillaries extend into the skin, and hair starts to grow on the scalp. The skeleton starts to develop and the fetus's nervous system starts to become active. Lastly, and most excitingly, the baby's heartbeat can be heard with a stethoscope during month four.

Month 5

sophiebarthel6 — 2024-10-20 04:58:26 UTC

Month five is arguably the most exciting, as the mother begins to feel the baby kicking. Alongside fetal movement, the fetus's body bends into the fetal position and becomes covered with a layer of fine hair called the lanugo. This helps to protect the baby's still-developing skin and is usually shed before the baby is born.

Month 6

sophiebarthel6 — 2024-10-20 05:04:16 UTC

By the sixth month, the baby has been growing steadily, and now the fetus's eyes have opened and eyelashes have started to form. The skin still appears pink, and now is very wrinkly, due there being very little fat beneath the skin layer. If the baby is born prematurely at this stage, it is very unlikely to survive without medical intervention.

Sterilization (pregnancy prevention)

georgiarfunk — 2024-10-20 20:56:39 UTC

If partners do not want to have a pregnancy, there are multiple ways one can sterilize to prevent it from happening.

natural family planning: avoiding intercourse during females time of ovulation prevents fertilization
physical/chemical barriers: condoms, spermicides (chemicals that kill sperm)
contraceptives: birth control pills (prevent LH and FSH release, female does not ovulate), IUDs (prevents implantation of zygote), plan B (+ progesterone/estrogen)
surgical: tubal ligation (ovum disintegrates, cannot be reversed), vasectomy (ductus deferens is cut to prevent release of sperm)

[these notes were based from the McGraw Hill manual]

Birth —>

georgiarfunk — 2024-10-20 22:10:32 UTC

The final steps in the baby’s journey of becoming a life

Parturition

georgiarfunk — 2024-10-20 22:15:15 UTC

This is the birthing process (labour) and it begins with uterine contractions. Oxytocin and prostaglandins help release the baby (positive feedback loop). The contractions stretch the cervix and stimulate uterine muscles to push the baby out.

The first two stages in parturition are the dilation stage (oxytocin makes cervix open), and the expulsion stage (head of baby rotates and gets pushed through the birth canal)

** relaxin is a hormone produced in the placenta to prevent premature birth, it also relaxes the pelvic joints during birth

Caesarean sections (c-section)

georgiarfunk — 2024-10-20 22:18:34 UTC

Reasons to do a c-section include: a breech birth (baby is exiting foot-first), premature birth (fetus is not fully developed yet), preventing an STI from the mother to pass onto the baby, mother has a small pelvis (could cause injury), preventing injury to the fetus during birthing process. This is performed through an incision in the mothers abdomen and physically removing the baby from the uterus.

Post infant birth

georgiarfunk — 2024-10-20 22:26:24 UTC

The baby’s umbilical cord is cut once birthed, and it turns into the navel (belly-button). Once born, the baby must acclimate to not having a direct resource to live from. It has to ingest food, breathe, and excrete wastes by itself (This can take some time to occur).

Afterbirth

georgiarfunk — 2024-10-20 22:31:28 UTC

This is the third and final stage of parturition, and it is when the umbilical cord, placenta, and extra-embryonic membranes are excreted from the uterus. This happens a few minutes after the baby is born.

Lactation —>

georgiarfunk — 2024-10-20 22:32:43 UTC

This is how breast milk produced and how the baby receives nutrients

Lactation (milk production & secretion)

georgiarfunk — 2024-10-20 22:36:51 UTC

After birth, the pituitary starts to secrete prolactin -> breast milk creation begins. As the baby suckles, nerve endings stimulate the release of oxytocin (positive feedback loop) which lets milk flow into mammary ducts from the glands. This process continues until milk is not needed by the baby anymore.

** the milk/colostrum has antibodies from the mother that helps protect the baby

Nicotine’s effect on breastmilk production

georgiarfunk — 2024-10-20 22:43:49 UTC

Through research experiments, scientists have discovered that nicotine has major effects on lactation. The nicotine lowers the amount of breast milk produced by the mother and it can contaminate the milk as well. This leads to slow infant growth and a nutrient deficiency in the baby.

Cite:

Author links open overlay panelVio F 1, et al. “Smoking during Pregnancy and Lactation and Its Effects on Breast-Milk Volume.” The American Journal of Clinical Nutrition, Elsevier, 1 Dec. 1991, www.sciencedirect.com/science/article/abs/pii/S0002916523319439.

The birth of a baby video

georgiarfunk — 2024-10-20 22:45:31 UTC

How lactation works video

georgiarfunk — 2024-10-20 22:50:13 UTC

How c-sections work video

georgiarfunk — 2024-10-20 22:54:19 UTC

Month 7

sophiebarthel6 — 2024-10-21 03:23:16 UTC

During this trimester, brain cells develop rapidly, and connect to form intricate networks in the baby's nervous system. At this time, the fetus turns to an upside down position, and testes of the male descend into the scrotum. Red blood cells are being formed in the baby's bone marrow. If at this point the baby is born prematurely, survival is likely.

Month 8

sophiebarthel6 — 2024-10-21 03:27:14 UTC

At month eight, the fetus begins to appear more "babyish" as fatty tissue develops beneath the skin layer, resulting in lighter and less wrinkled skin. This is the time where twins are usually born.

Month 9

sophiebarthel6 — 2024-10-21 03:33:34 UTC

In the final month of pregnancy, more fat develops beneath the skin layer and the lanugo hair layer is shed - the baby is about to be born!

Nutrition

sophiebarthel6 — 2024-10-21 03:37:04 UTC

While maintaining proper nutrition throughout the entirety of pregnancy is important, it is especially crucial during the third trimester. Nutrition affects both the mother and the fetus. Poor nutrition can damage the placenta, leading to many problems such as low birth weight, short stature, and learning disabilities.

Teratogen: nicotine's effect in trimesters two and three

sophiebarthel6 — 2024-10-21 04:20:43 UTC

While the effects of nicotine in the second and third trimesters won't be as severe as in the first trimester, smoking while pregnant has a number of serious effects.

Nicotine causes many issues after birth as well as during fetal development. Children born to a mother who smokes often exhibit respiratory infections (such as asthma) and are more at risk of infantile colic, bone fractures, and childhood obeisity.

Technology used in premature births

sophiebarthel6 — 2024-10-21 04:25:28 UTC

When a baby is born prematurely, especially at the six month mark, they need a significant amount of medical help to stay alive. The respiratory and the digestive systems are the last to develop during pregnancy, therefore if the baby is born prematurely, they won't be able to breathe very well and will have difficulty digesting milk. A couple examples of machines used to aid premature babies are:

ECMO machines (extracorporeal membrane oxygenation)

takes blood from the baby and pumps it through an artificial lung to oxygenate the blood and return it to the baby's circulatory system
special technique used for babies with respiratory issues

CPAP machines (continuous positive airway pressure)

pushes air into the baby's system to keep the very small airways into the lungs open and allows for the baby to get the amount of oxygen they need
administered through either tubes inserted into the nostrils or through a breathing tube in the baby's trachea