The basal body temperature rises after ovulation due to?

Appeared in: CGHS SSC - 2018

Explanation

After ovulation, the corpus luteum forms and secretes large amounts of progesterone.
Progesterone has a thermogenic effect, meaning it causes an increase in body temperature.
This hormone acts on the thermoregulatory center in the brain (hypothalamus), resetting the body's thermostat to a slightly higher level.
This results in a sustained rise in basal body temperature (BBT) of about 0.3°C to 0.5°C (0.5°F to 1.0°F), which is a key indicator that ovulation has occurred.

Option A: Inhibin's primary role is to inhibit the secretion of Follicle-Stimulating Hormone (FSH) from the pituitary gland; it does not have a thermogenic effect.
Option C: Relaxin is a peptide hormone primarily involved in relaxing pelvic ligaments and the cervix to facilitate delivery; it has no known effect on body temperature.
Option D: Oestrogen is the dominant hormone in the follicular phase (before ovulation) and is associated with the lower, baseline body temperatures seen in the first half of the cycle.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal control of basal body temperature during the menstrual cycle as background academic context rather than a clinical decision trigger.
Nurses educate patients on using Basal Body Temperature (BBT) charting as a method of natural family planning to identify the fertile window and confirm ovulation.
A sustained rise in BBT for more than 18 days after ovulation is a probable sign of pregnancy, as the corpus luteum continues to produce progesterone under the stimulation of hCG.
What if? If a patient's BBT chart consistently shows no sustained temperature rise (a monophasic pattern), it may indicate an anovulatory cycle. The nurse should recognize this as a potential cause of infertility and advise the patient to consult a healthcare provider for further evaluation.

How to Approach the Question

First, analyze the question to identify the key physiological event: a rise in basal body temperature (BBT).
Next, note the timing of this event: 'after ovulation'.
Recall the two main phases of the menstrual cycle: the follicular phase (pre-ovulation) and the luteal phase (post-ovulation).
Identify the dominant hormone of the luteal phase. The corpus luteum forms after ovulation and primarily secretes progesterone.
Connect the dominant hormone to the physiological event. Recall or deduce that progesterone has a thermogenic (heat-producing) effect.
Eliminate the other options by recalling their primary functions: Oestrogen is dominant before ovulation, Inhibin regulates FSH, and Relaxin is mainly for pregnancy/childbirth.

Concept Tested & Keywords

Concept Tested: Hormonal control of basal body temperature during the menstrual cycle.
Stem keywords: basal body temperature, ovulation, rises
Lead-in keywords: due to

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Practise the full CGHS SSC - 2018

Attempt every question from this paper in a timed mock, then review the full solution for each one.