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Question #45468
The Question
A 4-month postpartum mother relying on lactational amenorrhea for contraception begins supplementing her infant's diet with formula. A few weeks later, she conceives despite not having resumed menstruation. Which of the following neuroendocrine changes is the primary physiological cause for the failure of this contraceptive method?
Options
- A.
A decrease in oxytocin secretion from the posterior pituitary directly stimulates the anterior pituitary to release gonadotropins.
- B.
Reduced suckling stimulus lowers maternal progesterone, lifting the negative feedback on the anterior pituitary to trigger ovulation.
- C.
A drop in prolactin levels removes the suppression of hypothalamic GnRH, leading to follicular development and a subsequent estrogen-induced LH surge.
- D.
Decreased prolactin levels directly stimulate the corpus luteum to secrete estrogen, causing a premature LH surge.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Prolactin|GnRH|FSH|LH|Progesterone
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse the roles of Prolactin (milk synthesis and GnRH inhibition) with Oxytocin (milk ejection).
Additionally, there is a common misconception that menstruation must resume before ovulation can occur; however, the first postpartum ovulation (driven by the restored estrogen-induced LH surge) precedes the first menstruation, making the 'prolactin-gap' a critical window for unintended conception.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Chemical Coordination and Integration - Class 11 |
| Concept | Progesterone/Estrogen Feedback |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |