When does the menstrual period typically start after the luteinizing hormone (LH) surge?

From the Guidelines

The menstrual period typically starts about 14-16 days after the luteinizing hormone (LH) surge. This timeframe is based on the average lifespan of the corpus luteum, which forms after ovulation and produces progesterone for approximately 14 days 1. The LH surge triggers ovulation, which usually occurs 24-36 hours after the surge begins. Following ovulation, if pregnancy doesn't occur, the corpus luteum degenerates, causing progesterone levels to drop, leading to the shedding of the uterine lining and the start of menstruation.

The relationship between the LH surge and menstruation is crucial for understanding fertility and predicting menstrual cycles. In the context of intrauterine insemination (IUI), timing is critical, and the method of triggering ovulation, such as using HCG injections or monitoring follicle growth by ultrasound, can influence the outcome 1. However, the fundamental biological process of the LH surge triggering ovulation and the subsequent formation and degeneration of the corpus luteum remains consistent, leading to menstruation approximately 14-16 days later.

Key points to consider:

• The LH surge is a critical trigger for ovulation.
• Ovulation typically occurs 24-36 hours after the LH surge begins.
• The corpus luteum produces progesterone for about 14 days after ovulation.
• If pregnancy does not occur, the corpus luteum degenerates, leading to a drop in progesterone levels and the start of menstruation.
• This process is consistent with an average 28-day menstrual cycle, though individual cycle lengths can vary 1.

From the Research

Menstrual Period After LH Surge

• The menstrual period typically starts after the luteinizing hormone (LH) surge, but the exact timing can vary from woman to woman 2, 3.
• Studies have shown that the LH surge can last anywhere from 5 to 11 days, with a mean duration of 7.6 days 2.
• After the LH surge, ovulation usually occurs, followed by the luteal phase, which lasts around 14 days 4.
• Menstruation typically occurs 14 days after ovulation, which is around 21-28 days after the start of the LH surge, depending on the individual's menstrual cycle length 4.
• However, it's essential to note that the timing of the menstrual period after the LH surge can vary due to individual differences in cycle length and hormone levels 3, 5.

Factors Influencing Menstrual Cycle Timing

• Follicle size and serum estrogen levels play a crucial role in determining the timing of the LH surge and subsequent menstrual period 5.
• The relationship between follicle size and serum estrogen is not strong enough to predict the LH surge confidently, but an estrogen rise is essential for inducing the LH surge 2, 5.
• Other factors, such as gonadotropin responsiveness, IGF binding protein expression, and vascularization, also influence the selection and progression of the dominant follicle 4.

Clinical Implications

• Understanding the timing of the menstrual period after the LH surge is essential for clinical practice, particularly in fertility treatments and family planning 3, 6.
• LH profiles should be compared with the range of profiles observed in normally fertile cycles, rather than the mean profile, to account for individual variability 3.
• The chronology of follicle and oocyte maturation after the LH surge-initiating rise is similar to that following chorionic gonadotropin (hCG) administration, allowing for timely oocyte collection and fertilization 6.