A Quick Reference Guide to Common Conditions Associated With Pregnancy

Osmosis Team
Published on Nov 30, 2023. Updated on Dec 1, 2023.

In today's Osmosis from Elsevier blog, we're exploring common pregnancy conditions - nausea, skin changes, constipation, and supine hypotension - along with the causes of those conditions, their symptoms, and effective treatments.

Pregnancy, typically spanning about forty weeks or nine months, is (quite literally) a transformative experience involving adaptions the human body makes to nurture and support a growing fetus. Some of these physiologic adaptations include dealing with nausea and vomiting, skin changes, constipation, and supine hypotension. 

Let’s discuss these common conditions seen during pregnancy.

A pregnant individual with morning sickness or nausea, kneeling in front of a toilet, with their hand on their head, looking very uncomfortable and distressed.

Nausea and Vomiting During Pregnancy

Commonly referred to as “morning sickness,” the nausea and vomiting expectant individuals experience is most common during the initial trimester and early second trimester (i.e., weeks 5-20). Contrary to the name, it can strike at any time of the day or night.

While the exact cause of nausea and vomiting is unknown, hormones like human chorionic gonadotropin (hCG), estrogen, and progesterone play crucial roles. For instance, increased progesterone, essential to maintaining the uterine lining, decreases smooth muscle contractility, which can decrease gastric motility, contributing to nausea and vomiting. 

Typically self-reported, the signs and symptoms of morning sickness are accompanied by normal vital signs during a physical examination. However, if they become severe and persistent, the patient’s vital signs may be abnormal, with signs of dehydration. When nausea and vomiting result in a loss of more than five percent of the patient’s pre-pregnancy weight and are accompanied by the presence of ketones in the urine, this is known as hyperemesis gravidarum (HG)

Diagnosis is typically based on history and a physical examination but can include lab tests such as a complete metabolic panel (CMP) to assess for dehydration and a urine dipstick to evaluate specific gravity and ketones. 

Treatment typically involves supportive care and, when necessary, antiemetics. Supportive care can include non-pharmacologic options like small, frequent meals, ginger tea, or alternative therapies such as acupuncture are recommended. Pharmacologic choices like pyridoxine (Vitamin b6) and doxylamine are used as first-line medications to treat nausea and vomiting during pregnancy. If symptoms persist, other antiemetic drugs may be added and can include diphenhydramine, dimenhydrinate, promethazine, or prochlorperazine. If symptoms persist despite first- and second-line treatments, other prescription drugs, such as ondansetron and metoclopramide, can be used. 

An illustrated list of of possible skin changes during pregnancy including the background, contributing factors, and treatments.

Skin Changes Due to Pregnancy

Skin changes commonly seen during pregnancy include chloasma and linea nigra. Chloasma, also known as melasma and often referred to as “the mask of pregnancy,” is an acquired skin pigment disorder. While the exact cause isn’t fully understood, the hormonal changes during pregnancy involving estrogen, progesterone, and melanocyte-stimulating hormone (MSH) appear to play a role. 

Appearing as irregular, blotchy, hyperpigmented patches during the second or third trimesters, chloasma is commonly seen on the cheeks, nose, lips, and forehead during the second or third trimester (though it can occur at any time during pregnancy). Diagnosis is typically based on the clinical presentation but can include a Wood’s lamp examination to assess the extent of chloasma, and a skin biopsy can be done if the diagnosis is uncertain. 

It typically requires no treatment and fades post-delivery, but if treatment is required, options include topical skin-lightening agents, like azelaic acid, hydroquinone, or tranexamic acid; chemical peels, like glycolic acid; and laser- or light-based therapies. Preventative measures include strict sun protection to limit sun exposure, using broad-spectrum sunscreens, and wearing wide-brimmed hats.

Linea nigra, Latin for “black line,” commonly appears as a dark vertical line on the abdomen, running from the umbilicus to the pubic bone, during the second trimester of pregnancy. Diagnosed clinically, its exact cause is currently unknown. However, the rise in MSH, estrogen, and progesterone likely contributes. Treatment is usually not required, as it tends to fade following delivery. 

A bottle of laxative powder.

Constipation During Pregnancy

Affecting about 25% of pregnant individuals, constipation is a common problem that is the result of increased progesterone, decreasing smooth muscle contractility, and contributing to constipation. Iron supplements, often prescribed for anemia during pregnancy, can make constipation worse. 

Signs and symptoms of constipation include abdominal pain or discomfort, difficult or infrequent bowel movements, and the passage of hard, pebbled stool, colloquially known as “pebble poop.” Pebble poop presents as small pieces of stool that have broken apart from a larger mass, resembling tiny pebbles. Severe or persistent constipation may lead to or worsen existing hemorrhoids, which are swollen, inflamed veins found in the anus and rectum that can cause pain and rectal bleeding.

Diagnosis of constipation relies on clinical presentation, with treatments involving lifestyle changes like switching to a fiber-rich diet (e.g., fruits and vegetables, whole grains, legumes, nuts), staying hydrated, regular exercise, and certain medications. If lifestyle changes fail, bulk-forming stool softeners, like psyllium, and certain stimulant laxatives, like bisacodyl, can be used and are typically safe for use in pregnancy.

An illustration of a pregnant person laying down on their back.

Supine Hypotension (Low Blood Pressure) During Pregnancy

Supine hypotension arises when the growing uterus compresses the inferior vena cava (i.e., the major vein responsible for returning blood to the heart), decreasing venous return and resulting in hypotension (low blood pressure). It affects around eight percent of pregnant patients in their second and third trimesters and can worsen as the pregnancy progresses, causing more compression. Symptoms include dizziness, low blood pressure, sweating, tachycardia, and nausea, typically appearing 3-10 minutes after lying down. In severe cases, individuals may lose consciousness. 

Diagnosis is based on the patient’s history and clinical presentation, potentially including a decrease in systolic blood pressure by at least 15-30 mmHg while the individual is in the supine position (lying on their back). 

Treatment includes positioning the individual into the left lateral position to relieve compression of the inferior vena cava and increase venous return. Preventing supine hypotension includes avoiding prolonged periods in the supine position (especially after 24 weeks) and adapting sleeping positions, favoring left side-lying, which can enhance venous return.

An illustration of a pregnant person hooked up to a monitor in a hospital bed.

About the Author

Alyssa Haag, BA, MS-4obtained a Bachelor of the Arts in Integrative Biology and Education from the University of California, Berkeley in 2019. She then spent a year as a Medical Assistant at a primary care office in New York City before entering medical school at Nova Southeastern University Dr. Kiran C. Patel College of Allopathic Medicine in Fort Lauderdale, FL. She will be obtaining her Doctor of Medicine degree (MD) in May of 2024 and is currently in the process of applying for a Family Medicine residency. Her passion for education and accessible patient education brought her to Osmosis, where she works as a scriptwriter and editor for the Osmosis Q&A project.


Kelsey LaFayette, DNP, ARNP, FNP-C, Nursing Content Manager
Lisa Miklush, PhD, RN, CNS, Senior Content Editor

Resources & References

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  • Lee NM, Saha S. Nausea and vomiting of pregnancy. Gastroenterol Clin North Am. 2011;40(2):309-vii. doi:10.1016/j.gtc.2011.03.009

  • Trottier M, Erebara A, Bozzo P. Treating constipation during pregnancy. Can Fam Physician. 2012;58(8):836-838.

  • Vora R, Gupta R, Mehta M, Chaudhari A, Pilani A, Patel N. Pregnancy and skin. Journal of Family Medicine and Primary Care. 2014;3(4):318. doi: