The relaxation and increased mobility of pelvic ligaments and joints during pregnancy are primarily caused by the hormone:

Estrogenis a steroid hormonethat rises significantly in pregnancy, produced mainly by the placentaafter the first trimester. It influences neurotransmitter regulation, particularly serotonin and dopamine, which are involved in mood control. Rapidly increasing estrogen levels contribute to mood swings, irritability, and emotional lability often reported during pregnancy. Normal estradiol levels increase from ~50–350 pg/mL (follicular phase) to >10,000–40,000 pg/mL in late pregnancy.

Rationale for correct answer

2.Estrogen fluctuations and high levels alter central nervous system neurotransmission, especially serotonin, leading to emotional instability and mood swings. This is the primary hormonal factor for psychological changes during pregnancy.

Rationale for incorrect answers

1.Human placental lactogen regulates maternal glucose metabolism and increases insulin resistance to ensure fetal glucose supply. It does not act directly on neurotransmitters or cause mood swings.

3.Insulin regulates blood glucose by facilitating cellular glucose uptake. While hypoglycemia or hyperglycemia can cause irritability, insulin itself is not the hormonal cause of mood swings in pregnancy.

4.Thyroxine (T4) regulates metabolism and oxygen consumption. Abnormal thyroid hormone levels can cause anxiety or depression, but normal pregnancy mood swings are not primarily due to thyroxine.

Take home points

• Estrogen is the main hormone responsible for mood swings in pregnancy.

• High estrogen levels affect serotonin and dopamine pathways in the brain.

• Human placental lactogen and insulin regulate glucose, not emotions.

• Thyroxine regulates metabolism; abnormal levels may mimic mood changes but are not typical causes.

Heartburn in pregnancyis primarily due to progesterone-induced relaxationof the lower esophageal sphincter, which allows gastric acid refluxinto the esophagus. Progesterone also delays gastric emptying and decreases gastrointestinal motility. Normal lower esophageal sphincter pressure decreases progressively during pregnancy, predisposing to gastroesophageal reflux. Symptoms usually peak in the second and third trimesters.

Rationale for correct answer

1.Heartburn is the burning substernal sensation caused by reflux of gastric acid. Progesterone relaxes the lower esophageal sphincter, allowing backflow of stomach contents. This is the most direct gastrointestinal discomfort linked with progesterone-induced relaxation.

Rationale for incorrect answers

2.Constipation in pregnancy is caused by decreased bowel motility and prolonged transit time due to progesterone’s effect on smooth muscle. However, it is not due to lower esophageal sphincter relaxation but rather intestinal smooth muscle relaxation.

3.Nausea is primarily related to increased human chorionic gonadotropin and estrogen levels, especially in the first trimester. It is not due to esophageal sphincter changes.

4.Gingivitis results from increased vascularity, edema, and hormonal effects on gingival tissue, often leading to bleeding gums. It is unrelated to sphincter relaxation or acid reflux.

Take home points

• Heartburn in pregnancy results from progesterone-induced relaxation of the lower esophageal sphincter.

• Constipation is also progesterone-related but involves reduced intestinal motility, not sphincter relaxation.

• Nausea is linked to elevated hCG and estrogen levels, particularly in early pregnancy.

• Gingivitis arises from vascular and hormonal changes in gingival tissues, not gastrointestinal reflux.