Steroids are produced in greater amount in pregnancy so that

Question

Accepted Answer

The correct option is 1:
The massive increase in steroid production during pregnancy, particularly of glucocorticoids (like cortisol) and mineralocorticoids (like aldosterone), is a fundamental physiological adaptation to sustain the developing fetus and placenta. The primary purpose of this increase, specifically related to mineralocorticoid action, is to stimulate the kidneys to reabsorb, or retain, **water and sodium** in the body. Pregnancy necessitates a substantial expansion of the maternal plasma volume—up to 40-50%—to ensure adequate blood flow to the uteroplacental unit and meet the metabolic demands of the growing fetus. Aldosterone, whose secretion increases in response to the activation of the Renin-Angiotensin-Aldosterone System (RAAS), is the main hormone driving this salt and water retention. Additionally, the high levels of cortisol, although primarily a glucocorticoid, also exhibit some mineralocorticoid activity, further contributing to the retention process. Therefore, the greater production of these steroids is essential for volume expansion, which is a critical prerequisite for a healthy pregnancy outcome.

The incorrect option is 2:
The statement "it increases secretion by endometrium" is an inaccurate representation of the main role of increased steroids in pregnancy. The endometrium, which transforms into the decidua upon implantation, undergoes profound changes primarily driven by progesterone, a key steroid, in the initial phase to make the uterus receptive. However, the *increase* in circulating steroids, such as the dramatic rise in aldosterone and cortisol, is geared toward systemic adaptations like volume expansion (as detailed in Option 1) rather than solely increasing endometrial/decidual secretion. Moreover, the decidua is highly secretory *before* the main steroid increases occur, making this a secondary or already-established function rather than the central reason for the continued *greater* steroid production throughout gestation.

The incorrect option is 3:
The claim that increased steroid production leads to "thyroid glands are more active than normal" is incorrect because the two endocrine systems are regulated independently. The primary drivers for changes in thyroid activity during pregnancy are the high levels of human chorionic gonadotropin (hCG), which has a weak Thyroid-Stimulating Hormone (TSH)-like effect, and the increase in Thyroid-Binding Globulin (TBG), which binds thyroid hormones. The production of the adrenal and sex steroids is controlled by different mechanisms—the Hypothalamic-Pituitary-Adrenal (HPA) axis and the fetoplacental unit. While both steroid and thyroid hormones change in pregnancy, the increase in steroid hormones is not the *cause* of the thyroid gland being more active.

The incorrect option is 4:
The option "All options are wrong" is definitively incorrect because Option 1, which states that water and sodium are retained in the body, represents a fundamental and well-documented physiological effect of the increased steroid production (specifically aldosterone and cortisol) required to support the massive maternal blood volume expansion during pregnancy. This physiological change is essential for fetal growth and placental perfusion, directly validating Option 1 as the correct function.