Author Archives: laurenhumphrey

May 4th Lecture on Reproduction

Today was definitely an interesting lecture with lots of great questions!  We started on slide 49 and finished on slide 76.  Don’t forget about the two review sessions this week…Thursday at 6:30pm and Saturday at 2pm, both in SI 3081!  Dr. Hartley is going to buy pizza for the Thursday night session so don’t miss it!!

First Question…Why do girls cycles sync together when they live in close proximity?

After much research, I discovered that it’s not actually the cycles syncing together, but rather just though illusion.  Because a females cycle can last anywhere form 21-35 days, with a 3-7 day menstruation in there, it’s quite possible that cycles will overlap.  It may not be completely synchronized on purpose, but because of the vast differences in length of cycles, is quite possible to share a few days with your neighbor or close friend.  Many studies have been done to figure out why cycles seem to sync together, but there hasn’t been any beneficial evidence to prove the synchronization.  Many scientists have noticed that it seems to occur between close friend groups and roommates as opposed to neighbors that don’t care for each other or friends that don’t live together.  More research is being conducted as it is quite an interesting topic, but it is probably best to know, especially for those boys living in the dorms with lots of girls, that the chances of all the girls having PMS at the same time is very slim!

For more information, here is a website I found that seems to be fairly helpful on the topic: Women’s cycles

Question 2: Can a spike in temperature be used to predict ovulation?

Unfortunately, no.  Research has been done to prove that a woman’s temperature will increase around ovulation, but occurs 12-24 hours after ovulation due to the increase in progesterone.  Some researchers believe this is too late to utilize maximum fertility, but some researchers believe that upon detection of a temperature increase, a woman is still able to conceive.  The changes in temperature will be very slight, so a basal body temperature (BBT) thermometer needs to be used in the morning when a woman first wakes up before even getting out of bed.  The temperature increase can be anywhere from 0.4 – 1.0 degrees, thus the need for the BBT thermometer as it can detect small temperature changes better than a regular thermometer.  If it were possible, though it hasn’t been proven to be yet, a woman is most fertile 2-3 days before the spike in temperature.  Until that is something that can be determined, there are a few other ways to determine when a woman will ovulate.  There will be a change in the woman’s cervical mucus, with most women saying this resembles raw egg whites and some women can even feel ovulation.  This condition is called Mittelschmerz and can last a few minutes to a few hours with most women experiencing a vibrating sensation, to mild achiness all the way to intense pain.

For more information, visit Ovulation Calculator

Question 3:  What causes morning sickness?

First off, morning sickness is a misnomer!  Nausea and vomiting can occur at any time of day for a pregnant woman, though most experience the worst of it in the morning, hence the morning sickness.

Fun fact: 75% of women experience nausea and vomiting during their pregnancy!

There is really no known reason as to why morning sickness occurs, but many think it is due to the many physical and hormonal changes that occur in a woman’s body during pregnancy.  hCG (human chorionic gonadotropin) is one hormone that is seen to be a culprit for morning sickness.  There is no known reason as to why, but it’s a prime suspect because the timing is right: nausea tends to peak around the same time as levels of hCG.  And, conditions in which women have higher levels of hCG, such as carrying multiples, are associated with higher rates of nausea and vomiting.  Another suspected hormone is estrogen due to the rapid rise in estrogen levels in early pregnancy.

Another reason is the enhanced sense of smell and sensitivity to odors that most pregnant women experience.  It’s not a well researched cause, but because certain aromas instantly trigger the gag reflex in a pregnant woman, many researchers believe it’s a culprit.  Estrogen is believed to be the cause of the increased sensitivity to odors, but again, this is not well researched so it’s still unclear.

The final reason is the pregnant woman’s tricky stomach.  Because a pregnant woman’s stomach is very sensitive, this is usually the cause of nausea and vomiting.  Not very many studies have been done to research this topic, but this is a large culprit.

Moral of the story: not much is known about these three topics, so if you kiddies have any interest in reproductive biology, you may be the first to discover something about the interesting topics above!

Final fun fact: high levels of hCG is often found in men with testicular cancer and is often used to aid in diagnosing and tracking the chemotherapy/radiation effectiveness! Men can take pregnancy tests too 🙂


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