Ovulation: The Dividing Line (Page 48-49 of text):

The first part of the cycle, from Day 1 of menses to ovulation, is the follicular (or estrogenic) phase. Its length can vary considerably. The second phase of the cycle, from ovulation to the last day before the new period begins, is the luteal (or progestational) phase. It usually has a finite lifespan of 12-16 days. What this means is that ultimately, it is the day of ovulation which will determine the length of your cycle.

For example, a woman could have an extremely delayed ovulation due to stress or other factors, not ovulating until Day 30 or so. This would result in about a 44 day cycle (30 plus 14.) Thus, just because a woman is on Day 44 and hasn't gotten her period yet doesn't necessarily mean she's pregnant.

My brother Raymond was editing the manuscript for this book when he got a call from his good friend Marcella, who lives in Los Angeles. She appeared mildly panicked about possibly being pregnant, and was calling him for advice (Ray was accustomed to his friends' inquiries, since he possessed a certain expertise on fertility that few men do).

She explained that she was worried because she was on Day 42 and had never had a cycle longer than 32 days. Clearly enjoying his role as supportive friend and menstrual detective, Ray proceeded to record all the relevant information. Sex with her boyfriend on Day 5. 'Sloppy withdrawal.' No cycles ever less than 25 days. And so on.

The data convinced Ray that pregnancy was extremely unlikely. He then went on to explain to Marcella that if she had been sick, or traveled, or had experienced a lot of stress before she ovulated, it was possible ovulation could have been delayed days or even weeks, thus causing the extended cycle. She was not terribly reassured. "You must have been stressed out about something" he said. Marcella insisted that all was basically uneventful in her life, and that the only unusual anxiety she was experiencing had crept in just a few days earlier, about a week after her last period was "due."

Beyond being a menstrual detective, Ray was also an amateur historian. He loved dates. He took out his calendar and stared at it. "Marcella" he said coyly, "let me just verify. Your last period started on January 6th, so you normally would've ovulated around January 20th, give or take a few days."

"Yeah, I guess," she mumbled nervously.

"So, I'm just curious, on January 17th, did you just sleep through the earthquake, or what?"

There was a pause.

"Oh God, I forgot about that! That was one of the scariest things I've ever been through. 6.7 on the Richter scale! It was awful." Ray laughed and told her to relax, that she almost certainly wasn't pregnant. Three days later Marcella called back, delighted to inform him that she had just gotten her period.

Ray suggested that the next time a massive quake strikes, the mayor should go on city-wide TV. That way he could assure the women of L.A. that if their periods are late, it’s quite possible there’s nothing to worry about. It could just be your garden-variety, seismically-delayed ovulation.