The Science Behind Menstrual Cramps: Understanding the Role of Prostaglandins

[Mr. Robin Parsons]

In zoopharmacology it has been observed females in estrus going to certain trees or plants and eating of them, they were later checked and found to have had compounds that would have (it is "believed" or "known" I'm not certain, recollection at this moment) eased the pains...so primates do have the physical discomforts...

 

[hitssquad]

The Willow tree story

In zoopharmacology it has been observed females in estrus going to certain trees or plants and eating of them

...Also known as the Willow tree.

 

[Moonbear]

*bangs head on desk*
Sorry, but I need to correct some glaring errors above.
First, menstruation is not when women are most fertile, in fact, it is when they are least fertile. A full menstrual cycle is 28 days (on average). Menstruation begins on day 1, ovulation happens around day 14...about 3 days before to 3 days after ovulation is when women are most fertile (this relates to the length of time the oocyte is viable in the oviduct and the length of time sperm can survive in the reproductive tract). Under unusual circumstances (i.e., stress or after stopping taking birth control when the body is still "relearning" to regulate itself), it is possible that a woman can ovulate while menstruating, so that is why people are reminded it is not a "safe" time to engage in intercourse, but it is not the norm.

Now for the advanced lesson:
In animals, estrus is the period around ovulation defined by increased mating activity (non-primates don't mate when they are not near the time of ovulation, but will instead run away from or turn aggressive toward a male that attempts to mate). Non-primates don't menstruate. Since many people are aware of the discharge dogs have when in heat, you should know that is not menstruation. Menstruation is the flushing of the uterine lining that occurs when primates have not become pregnant, and the uterine lining regrows during the two weeks leading to ovulation. In dogs, the bleeding and discharge are from the cervix and serve to attract a mate and provide the same lubrication function that cervical mucous provides in women.

In animals that don't menstruate, there wouldn't be any menstrual cramping because there are no uterine contractions necessary to expel the lining. In most animals, it is simply resorbed by the body with no discharge. Cramping is due to the contraction of the uterus to expel the lining that is flushing out, which is facilitated by prostaglandins. However, prostaglandins serve another function at that time, which is to induce the "death" of the corpus luteum. When a woman ovulates, the cells that previously surrounded the ovum (follicles), transform into a structure called the corpus luteum that secretes progesterone. If the woman becomes pregnant, the progesterone produced by the corpus luteum helps maintain that pregnancy. If she doesn't become pregnant, then the corpus luteum needs to "die" to allow the new follicle to mature (progesterone inhibits follicle development and ovulation in women). Prostaglandin F2alpha is secreted by the uterus and targets the ovary to kill off the corpus luteum so the next follicle will develop. That time between the death of the corpus luteum, when progesterone concentrations drop very low, and until the new follicles start maturing and producing estrogens, is when menstruation occurs. The effects on mood are related to the very low concentrations of the ovarian steroids (progesterone and estradiol, which is an estrogen). The precise mechanism for that is not fully known, other than that neurons in the brain that contain receptors for estrogen are located in places that make them good candidates to modulate serotonin concentration (serotonin is the neurotransmitter implicated in depression). But that is a very oversimplified explanation.

To the question of whether other animals get PMS, since only primates menstruate, non-primates, by definition, can't get PMS. Except for the few days around estrus when females are willing to mate, they're pretty mean to the males anyway, so it may be that PMS is actually a shorter duration of aggression toward males in a species that relies on a long duration of paternal care for raising offspring than happens in species where the males take off as soon as mating is done. Then again... ;)

 

[Mr. Robin Parsons]

...Also known as the Willow tree.

Uhhmmmm NO not the one mentioned in the article I had read...not that I recall...

 

[Jenn_ucsb]

I think that we aren't simply innocent bystanders, rather the cause (in a sense) of the attacks on us.
I think that the physical pain and discomfort is only a part of it, the driving cause is emotional.
My theory is that this goes way back in our evolutionary past.
When females are menstruating, not only will males be more ummmm... frisky, but women know that they are running a higher risk of pregnancy.
Males, being the aggressors, would be... well, aggressive and women would have to fight them off if they weren't interested.

I would love to do a study on primates to see if they experience PMS and, if so, whether or not it directed specifically at males or just radiates ourward at whomever is arond (I would also be curious about other species).

I have always thought that there is some hormone that is released which make women more aggressive and assertive and makes them more protective of their bodies when men are around.
Or perhaps, it is not specifically directed AT males, but the production of this hormone is amped up when males are around (maybe as a reaction to the male pheremones?).

Anyone know of any such study?
Does my hypothesis retain (oh, sorry, I meant hold) water?

One_raven,
I hope you don't rely on the rhythm method for birth control! Menstruation is one of the least likely times for a woman to get pregnant. I think if there is any good reason why some women get a little pissy (mind you, I said some because not all do), it would be because they are experiencing pain and discomfort. No one likes pain - you'd be irritable too.

 

[Mr. Robin Parsons]

One_raven,
I hope you don't rely on the rhythm method for birth control! Menstruation is one of the least likely times for a woman to get pregnant. I think if there is any good reason why some women get a little pissy (mind you, I said some because not all do), it would be because they are experiencing pain and discomfort. No one likes pain - you'd be irritable too.

Heck, I'm a guy, and I agree with that!

 

[Monique]

One_raven,
I think if there is any good reason why some women get a little pissy (mind you, I said some because not all do), it would be because they are experiencing pain and discomfort. No one likes pain - you'd be irritable too.

That too, but many women suffer from PMS, prémenstrual syndrome, where in fact hormonal imbalances cause the irritabel/emotional state of mind.

 

[one_raven]

That too, but many women suffer from PMS, prémenstrual syndrome, where in fact hormonal imbalances cause the irritabel/emotional state of mind.

Exactly.
I thought it's called PMS because it happens before menstruation.

 

[Moonbear]

Exactly.
I thought it's called PMS because it happens before menstruation.

Yes, it begins before menstruation in many women, but can continue throughout the period of menstruation. The physical symptoms can begin a few days before the onset of menstruation as well. The increase in prostaglandins and decrease in circulating steroids begins several days before menstruation. Many women experience not only abdominal discomfort, but also back pain and headaches, in addition to the effects on mood.

There is also a more severe form called premenstrual dysphoric disorder (PMDD) . PMDD is currently treated with SSRI's (I'm not sure if this is an approved therapy or still in clinical trials, but I've seen many reports in the literature on it), so may reflect a mild underlying disposition to depression that increases in severity when hormone concentrations drop. PMDD is considered a bona fide psychiatric disorder and is treated as such.

 

[one_raven]

So...
Since PMS starts a few days before ovulation... during PMS, women are quite likely to get pregnant, right?

 

[Jenn_ucsb]

So...
Since PMS starts a few days before ovulation... during PMS, women are quite likely to get pregnant, right?

Oh lordy, dear one_raven, PMS stands for premenstrual syndrome. It precedes menstruation, not ovulation. They are different things. Please go read up on this. Here's a good visual summary for the scientifically inclined:
http://www.people.virginia.edu/~rjh9u/menscyc3.html

And please, no sex until you understand this.

 

[one_raven]

Really?!
Its s good thing I use condoms!

 

[one_raven]

I always thought it went something like this:

Day 1 (start of PMS): Egg drops down to the Uterus. Woman can get pregnant.
Day 4 or 5: If the egg was not fertilized, menstruation starts and the egg is washed from the system with blood.
Day 8 or 9: Egg is gone, 20 more safe days to go.

Go figger.

 

[adrenaline]

Day 1 (start of PMS): Egg drops down to the Uterus. Woman can get pregnant.
Day 4 or 5: If the egg was not fertilized, menstruation starts and the egg is washed from the system with blood.
Day 8 or 9: Egg is gone, 20 more safe days to go.

Assuming a 28 day cycle, ovulation usually occurs around 2 weeks before menstruation, as someone has already reiterated. PMS usually starts during the week of the very rapid decline of both estradiol and progesterone which is usually the 7 days before menstruation and may continue througout the menstruation. The egg can be fertilized anywhere between the time it enters the fallopian tubes and the uterus , most of the time it is already fertilised and dividing by the time it is deposited in the uterus.

 

[Moonbear]

One_Raven, please please please read carefully what Adrenaline just posted and what I have posted up closer to the top of the page here about the timing of the menstrual cycle. Ovulation occurs about 14 days AFTER the start of menstruation (or before...it's a cycle, so depends on which way you want to think about it).

If you don't mind sharing, can you please tell me where you learned about reproduction? This is not the first time I've heard someone have it completely backward about when ovulation is relative to menstruation, so I'm wondering if this is something that needs improving in how it's presented in schools. The reason I ask is that my primary area of research is on the reproductive system, and I belong to a professional society that promotes education and outreach on reproductive issues. I always thought these basics were covered in most schools nowadays, so I'm wondering where the confusion begins and how to address it. Is it that kids just aren't listening in class, or that it's being taught wrong or in a confusing manner, or are there schools where this still isn't being taught at all and kids are still getting the same wrong information repeated by their parents or peers? The last person I spoke with who had the same misinformation you did had attended a Catholic school quite a while ago, when Catholic schools pretty much avoided any discussion at all of reproductive biology and left that up to parents. Clearly that didn't work very well.

 

[one_raven]

I went to public school in New Jersey.
We did have sex-ed (or health class, as they called it) but the information was not covered very well, and was presented in a pretty rough and confusing manner.
So, the blanks were filled in by what other confused people told me.
The way they explained it made sense.
There were days that the boys ang girls were separated (I assume to avoid embarrassment) to discuss the "boy stuff" with the boys and the "girl stuff" with the girls, and I imagine they covered menstruation with the girls in more detail on those days.

You have to remember, though, this was about 20 years ago.
I was one of the first classes to get sex-ed in my town.
I don't know how it is now.

 

[Moonbear]

Hey, cool, I grew up in NJ too! Probably going through the schools at about the same time...though in our school system, we had sex ed (yes, also called health class then) EVERY year from about 5th grade through senior year. The only year we didn't have sex ed in health class was the year it was replaced with driver's ed. We started getting sick and tired of the same stuff every year, but it sure made for an easy A after a while. I didn't realize there was so much variation even in the same state. I thought the curriculum was fairly standardized across the state educational system. Of course we had the advantage in my school that the health teacher was a former OB nurse, so she really knew her stuff. We also only separated boys and girls the first year (fifth grade), when they basically were explaining what to expect as puberty began. After that, all sex ed was with both sexes present. That makes more sense to me than separating the sexes since everyone needs the same information.

Anyway, thanks for sharing that. I wonder if things have improved since then. I hope so. I think it's important to start with the basics and gradually build upon that. It's good to teach anatomy, but I think too many schools focus entirely on the reproductive anatomy and leave out the important things like when ovulation actually happens and how long sperm can live. It's probably an attempt at avoiding giving kids the illusion there are "safe" times of the cycle when teenage girls especially can have incredibly variable cycle lengths.

 

[one_raven]

Hey, cool, I grew up in NJ too!

If it's not too personal, where in NJ, and how old are you?

 

[Moonbear]

If it's not too personal, where in NJ, and how old are you?

Well, since it wasn't exactly a small town, it's not like you or any other potential internet wackos are going to track me down based on where I grew up. I'm originally from East Brunswick.

But a lady never divuldges her age Hee hee...how about I stick with somewhere in my 30s.

Your turn. If it turns out we were potential neighbors or something, we should take this discussion off the board since I don't think catching up on old-times in NJ is exactly the focus of the biology topic (I think this site came with some way to set up a free email account with membership...I'll look into that).

 

[Monique]

Besides the email account, you are able to send private messages (PMs) to other members. Click on the profile to find a link, or look at the top of the page to the right :)

 

[The_Professional]

In my country, I went to a private Catholic school for boys and we had sex education taught by priests. YIKES!

 

[Kerrie]

So...
Since PMS starts a few days before ovulation... during PMS, women are quite likely to get pregnant, right?

ovulation occurs approx 2 weeks prior to mentruation, during the two weeks after ovulation ( I think ) the egg comes down the fallopian tubes into the uterus...

 

[Kerrie]

I think they should if menstrual cramps can already be that bad, I am afraid what the labour cramps are going to feel like

that depends on your tolerance of pain...i have had to vaginal births of my children, the first i had an epideral, the second i had nothing for pain. with the epidural, i was unable to walk, had to remain in bed with a catheter (which is the most uncomfortable thing ever), remained in labor for 19 hours and when it came time to deliver i had no idea what to do because i couldn't feel a thing. when i had my second child, labor was only 4 hours (mostly due to it being my second) and when it came to time to deliver, i knew when to push because the contractions were being felt...yes, it hurt, but you forget that pain once the 30 minutes is over and you are holding your child that you had been carrying for 9 months. i have heard that active women can tolerate pain more because their endorphins kick in faster, not sure how accurate this is.

 

[Evo]

that depends on your tolerance of pain...

Very true, but there can also be other factors. My mother felt no pain and had 4 children. She didn't even know she was in labor with my little sister. She told me that labor pains were a "little twitch". This is a woman that is flat on her back if she has even a little headache, so I figured I would have no problem with labor pain.
WRONG!

My first labor was 42 hours of the most excrutiating pain I can imagine the human body enduring. Imagine having the entire inside of your body being slowly ripped inside out. I had several epidurals, THANK GOD for EPIDURALS! It was the only relief I had. Kerry, it sounds like you went into labor too soon after the epidural was administered, usually the epidural is allowed to wear off prior to delivery time. My daughter never turned and was born face up. Her back was pressed against my spine the entire time. My upper left leg had no feeling for 6 months after she was born. The GOOD news is, that thanks to the epidural, I was strong enough at delivery to push her out on the third push. The doctor was amazed. I would not have been able to without the epidural allowing me to rest.

And I have NEVER forgotten the pain. My heart is racing right now even writing about it.

I did have a second child, less than 32 hours in labor. A lot less painful, but I did have epidurals. It took me 6 pushes to get her out 9LBS 6 OZ. A little heffer.

BTW, I have very painful menstrual cramps normally.

 

[Monique]

that depends on your tolerance of pain...

I guess it would depend more on the kind of pain.. your stories are impressive though :)

 

[one_raven]

Your turn. If it turns out we were potential neighbors or something, we should take this discussion off the board since I don't think catching up on old-times in NJ is exactly the focus of the biology topic

Not exactly neighbors.
I grew up in Clifton and Elmwood Park.
Little more than an hour north of you.
10 minutes West of NYC.

I'm 32, by the way.

 

[Njorl]

A word of advice to you guys out there. Do not attempt to alleviate your wife's labor pains with "a little humor". If my wife had a gun, she would have shot me. I don't remember what I said, but I swear when she turned her head and glared at me I heard the pump action of a shotgun.

She had a painful time of it. The damn anaestesiologist missed with the epidural. They refused to give her another one for fear of overmedicating her. When they finally did give her another, it kicked in right before delivery, and she had a real hard time pushing.

Njorl

 

[Moonbear]

Njorl, it really depends on your wife. Then again, maybe it was just a bad joke :-) When my sister was in labor, we were joking quite a bit...actually, I think my brother-in-law said something stupid (not uncommon with him) and she looked at him and asked, definitely joking, "Is this when I'm supposed to say we're never having sex again?"

There have actually been recent studies that it's better to not get an epidural. Epidurals can slow the contractions and extend the time of labor. There have also been reports of more vaginal tearing during delivery in women with epidurals. There's a slower recovery afterward, including more problems with lower back pain and numbness in the legs. There are also reports that it can leave the baby more lethargic upon delivery too so they don't nurse as well in that first feeding right after delivery.

Of the women I've known who have gone through labor without epidurals, either by choice or because there was a reason they couldn't get it (too far progressed by the time they got to the hospital, some contraindication, etc), they've all seemed to have very short labors (hard labor was only about an hour and a half...that's the part that really hurts...the rest they said hurt, but was tolerable), and within hours of delivery already seem to forget the severity of it. The main thing that they all say makes it tolerable is knowing it will be over. Usually their husband's recollection is far better than their own.

Of those who had epidurals, their labor was so much longer...to the point where many of them have wound up getting oxytocin (something they'd never wish on their enemies they tell me...oxytocin injection induces far stronger contractions than normal labor, and apparently far more painful...those women all still remember that pain). One even had to have the epidural stopped because it slowed labor so much...once it was stopped, labor progressed normally.

Anyway, that's all anecdotal, but it's been such a consistent pattern among my friends and relatives that I certainly plan to go for a drug-free delivery when it's my turn.

 

[adrenaline]

I was in labor 24 hours, probably because I had worked a 15 hour shift just beforehand. I could not get an epidural since I was on Lovenox (low molecular weight heparin) for Factor V Leyden disease (my twin already had a huge pulmonary embolism). No sedation. I thought I was tough since I have broken major bones and kept racing during some of my mountain bike races ( finished a race with a posterior dislocated shoulder and another with a radial head fracture) so I thought I was tough cookie and everyone else were just being pansies... But the pain was excrutiating! I yelled at my husband and told him he was counting all wrong. Then,as Chief of Medicine I ordered my OB to give me a damn epidural anyway and I would not sue him if I had a spinal bleed and got paralyzed. He just laughed and told me I was not of right mind and he only took his orders from the Chief of Surgery. I think I threw a kidney basin at him. Anyway,the point is, I thought I could anticipate the pain but boy was I wrong!

 

[Evo]

There have actually been recent studies that it's better to not get an epidural. Epidurals can slow the contractions and extend the time of labor. There have also been reports of more vaginal tearing during delivery in women with epidurals. There's a slower recovery afterward, including more problems with lower back pain and numbness in the legs. There are also reports that it can leave the baby more lethargic upon delivery too so they don't nurse as well in that first feeding right after delivery

Of the women I've known who have gone through labor without epidurals, either by choice or because there was a reason they couldn't get it (too far progressed by the time they got to the hospital, some contraindication, etc), they've all seemed to have very short labors (hard labor was only about an hour and a half...that's the part that really hurts...the rest they said hurt, but was tolerable), and within hours of delivery already seem to forget the severity of it. The main thing that they all say makes it tolerable is knowing it will be over. Usually their husband's recollection is far better than their own.

Of those who had epidurals, their labor was so much longer...to the point where many of them have wound up getting oxytocin (something they'd never wish on their enemies they tell me...oxytocin injection induces far stronger contractions than normal labor, and apparently far more painful...those women all still remember that pain). One even had to have the epidural stopped because it slowed labor so much...once it was stopped, labor progressed normally.

Anyway, that's all anecdotal, but it's been such a consistent pattern among my friends and relatives that I certainly plan to go for a drug-free delivery when it's my turn.

I agree a lot of women have easy labor and don't need an epidural. Why they do not understand some women aren't as lucky really makes me angry. I would compare their labor to a paper cut and I was undergoing major surgery.

My contractions started before the baby dropped, I wasn't dilating, I was bleeding so heavily the blood was dripping off the side of the hospital bed, the nurses couldn't replace the pads under me fast enough.

The women that didn't have epidruals and said "oh' it's not that bad, & I don't remember the pain, blah, blah, blah", are like my mother, she didn't experience pain. My girlfriend had very moderate pain & a quick delivery. I know women that had just the opposite, like me. The women you are talking about are lucky, they don't know how severe the pain can be.

I did notice that the women that didn't have epidurals had much more trouble pushing than I did. They were so exhausted after even a few hours of labor that they didn't have the strength to push properly. Thanks to the epidural, I was able to rest, and I had no trouble pushing.

Moonbear, I hope for your sake you're one of the lucky ones that has a fast, relatively painless delivery.

Adrenaline, I know what you went through. I'm surprised you didn't harm anyone.