Pregnancy is the time period between fertilization Fertilization To undergo fertilization, the sperm enters the uterus, travels towards the ampulla of the fallopian tube, and encounters the oocyte. The zona pellucida (the outer layer of the oocyte) deteriorates along with the zygote, which travels towards the uterus and eventually forms a blastocyst, allowing for implantation to occur. Fertilization and First Week of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine Urine Liquid by-product of excretion produced in the kidneys, temporarily stored in the bladder until discharge through the urethra. Bowen Disease and Erythroplasia of Queyrat test) and pelvic ultrasound. There are numerous maternal adaptations to pregnancy, both anatomic and physiologic, which occur to help support the developing fetus and prepare the mother's body for ultimate delivery. Pregnancy is not a pathologic condition, but good routine prenatal care Prenatal care Prenatal care is a systematic and periodic assessment of pregnant women during gestation to assure the best health outcome for the mother and her fetus. Prenatal care prevents and identifies maternal and fetal problems that adversely affect the pregnancy outcome. Prenatal Care can help achieve the best outcomes for both the mother and infant. Prenatal care Prenatal care Prenatal care is a systematic and periodic assessment of pregnant women during gestation to assure the best health outcome for the mother and her fetus. Prenatal care prevents and identifies maternal and fetal problems that adversely affect the pregnancy outcome. Prenatal Care includes appropriate lab and ultrasound testing, anticipatory guidance, and offering solutions or advice for common pregnancy discomforts.
Last updated: 3 Apr, 2022
Pregnancy is defined as the time period between fertilization Fertilization To undergo fertilization, the sperm enters the uterus, travels towards the ampulla of the fallopian tube, and encounters the oocyte. The zona pellucida (the outer layer of the oocyte) deteriorates along with the zygote, which travels towards the uterus and eventually forms a blastocyst, allowing for implantation to occur. Fertilization and First Week of an oocyte and delivery of a fetus approximately 9 months later.
Individuals trying to get pregnant will typically present with a positive home pregnancy test. Many others may not know they are pregnant and will present with symptoms of early pregnancy, which may include:
Pregnancy is confirmed based on lab tests and obstetric ultrasound imaging.
The major analyte Analyte The molecule of interest (antigen) Immunoassays used to establish pregnancy is β-hCG.
Yolk sac
Yolk Sac
The first of four extra-embryonic membranes to form during embryogenesis. In reptiles and birds, it arises from endoderm and mesoderm to incorporate the egg yolk into the digestive tract for nourishing the embryo. In placental mammals, its nutritional function is vestigial; however, it is the source of intestinal mucosa; blood cells; and germ cells. It is sometimes called the vitelline sac, which should not be confused with the vitelline membrane of the egg.
Embryoblast and Trophoblast Development inside a gestational sac:
The
yolk sac
Yolk Sac
The first of four extra-embryonic membranes to form during embryogenesis. In reptiles and birds, it arises from endoderm and mesoderm to incorporate the egg yolk into the digestive tract for nourishing the embryo. In placental mammals, its nutritional function is vestigial; however, it is the source of intestinal mucosa; blood cells; and germ cells. It is sometimes called the vitelline sac, which should not be confused with the vitelline membrane of the egg.
Embryoblast and Trophoblast Development is the “white circle,” which is inside the gestational sac (the “black circle”).
GSD: gestational sac diameter
GA: gestational age (based on GSD measurement)
D: diameter
Intrauterine pregnancy within a gestational sac:
The image on the right shows the measurement of the
crown-rump length
Crown-Rump Length
Obstetric Imaging. The fetal head is on the left and the rump is on the right. Early limb buds are also present. The
placenta
Placenta
A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones).
Placenta, Umbilical Cord, and Amniotic Cavity is on the bottom of the gestational sac in these images.
Establishing the EDD is one of the most important factors to accomplish after diagnosing a pregnancy. Dating a pregnancy is usually done by calculating the EDD from the LMP and comparing that date with the EDD obtained from early ultrasound measurements.
To support fetal growth and development and prepare the mother’s body for eventual delivery, numerous anatomic and physiologic changes occur within a woman’s body during pregnancy.
Uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy:
Cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy:
Ovaries Ovaries Ovaries are the paired gonads of the female reproductive system that contain haploid gametes known as oocytes. The ovaries are located intraperitoneally in the pelvis, just posterior to the broad ligament, and are connected to the pelvic sidewall and to the uterus by ligaments. These organs function to secrete hormones (estrogen and progesterone) and to produce the female germ cells (oocytes). Ovaries: Anatomy:
System | Parameters that ↑ in pregnancy | Parameters that ↓ in pregnancy | Symptoms and anatomic changes |
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Cardiovascular system |
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Hematologic system |
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Respiratory system |
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GI system | Intraabdominal pressure |
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Renal system |
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Endocrine and metabolic systems |
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Physiologic maternal changes in the cardiovascular system during pregnancy: percent change over nonpregnant values
Image by Lecturio. License: CC BY-NC-SA 4.0Physiologic maternal changes in the cardiovascular system during pregnancy: percent change over nonpregnant values
Image by Lecturio. License: CC BY-NC-SA 4.0Linea nigra and hyperpigmentation Hyperpigmentation Excessive pigmentation of the skin, usually as a result of increased epidermal or dermal melanin pigmentation, hypermelanosis. Hyperpigmentation can be localized or generalized. The condition may arise from exposure to light, chemicals or other substances, or from a primary metabolic imbalance. Malassezia Fungi of the umbilicus in pregnancy
Image: “Linea nigra” by Daniel Lobo. License: CC BY 2.0The typical schedule of prenatal visits for low-risk individuals:
Parameters to measure/monitor for healthy, uncomplicated individuals at routine prenatal visits:
All pregnant individuals should have certain labs done at different points during their pregnancy. These include:
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Weight gain:
The recommended weight gain during pregnancy is based on the individual’s prepregnancy BMI BMI An indicator of body density as determined by the relationship of body weight to body height. Bmi=weight (kg)/height squared (m2). Bmi correlates with body fat (adipose tissue). Their relationship varies with age and gender. For adults, bmi falls into these categories: below 18. 5 (underweight); 18. 5-24. 9 (normal); 25. 0-29. 9 (overweight); 30. 0 and above (obese). Obesity. Normal weight-gain recommendations:
Exercise:
The primary symptom of pregnancy is a “missed” menstrual cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation. Pregnancy must always be ruled out using a simple urine Urine Liquid by-product of excretion produced in the kidneys, temporarily stored in the bladder until discharge through the urethra. Bowen Disease and Erythroplasia of Queyrat-pregnancy test in reproductive-aged women presenting with abnormal bleeding. Other common causes of abnormal uterine bleeding Abnormal Uterine Bleeding Abnormal uterine bleeding is the medical term for abnormalities in the frequency, volume, duration, and regularity of the menstrual cycle. Abnormal uterine bleeding is classified using the acronym PALM-COEIN, with PALM representing the structural causes and COEIN indicating the non-structural causes. Abnormal Uterine Bleeding include:
Some individuals may present with pelvic pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways and/or bleeding, which are symptoms that are more concerning for an abnormal pregnancy. Again, pregnancy should always be tested for in these individuals using a urine Urine Liquid by-product of excretion produced in the kidneys, temporarily stored in the bladder until discharge through the urethra. Bowen Disease and Erythroplasia of Queyrat-pregnancy test. If the test is positive, the differential diagnosis includes: