Blood Clots After IVF

Women sometimes develop blood clots in their veins (venous thromboembolism) or pulmonary arteries (pulmonary embolism) during pregnancy.   The development of blood clots during normal pregnancy is a rare event, but when it occurs but it can be potentially serious.

Women who are contemplating IVF (in vitro fertilization) should be aware that according to a recent report, the risks of developing venous blood clots during an IVF-induced pregnancy are about 77% higher than during a normal pregnancy.   The risk is especially increased during the first trimester. However, the absolute risk is still fairly low; about 4.2 cases per 1,000 pregnancies.  It’s nothing to worry about unduly, but perhaps it’s something that should be discussed with one’s doctor before undergoing IVF.

The authors hypothesize that perhaps the reason for the increased risk is that high doses of estrogen generally are used to stimulate egg development prior to egg collection in an IVF procedure.   Exogenous estrogen (in birth control pills or in hormone replacement therapies after menopause) is known to be associated with venous thromboembolism.   This raises an interesting untested question – would women who undergo an IVF procedure but who do not become pregnant also be at increased risk for blood clots?  As far as I know, that has never been tested.

Exercise and the Flu Vaccine

Exercising immediately after receiving a flu vaccine enhances the effectiveness of the vaccine, according to researchers at Iowa State University. In the study, young adults who received the flu vaccine either participated in a mild-to-moderate exercise regimen for 90 minutes immediately after receiving the vaccine, or remained sedentary for 90 minutes. Participants who exercised immediately after receiving the vaccine showed a greater level of antibody production than students who remained sedentary. Presumably the higher level of antibody production would better protect the participants who exercised against the flu, but apparently that wasn’t specifically tested in this study. (The study has not yet been published in a peer-reviewed journal.)

The mechanism whereby exercise enhances the effectiveness of the flu vaccine isn’t known yet. The study’s lead researcher speculates that by improving blood flow to some tissues, exercise may speed the delivery of the vaccine to the lymph nodes, where most antibody production takes place. But that remains to be tested.

So go ahead and exercise immediately after the flu shot if you want to: it appears to do more good than harm.

Pregnancy and the Flu Vaccine

Is it okay for pregnant women to get a flu shot? The answer is “yes”, according to a study conducted in Norway recently. (The research was conducted in Norway because access to health care in Norway is nearly universal, and good records are kept.) The results of the study are published in the New England Journal of Medicine. 

 The researchers reviewed the outcomes of the pregnancies of over 100,000 women in Norway during 2009 and 2010, about half of whom received the flu vaccine during the second or third trimester (the other half served as the control group). As expected, vaccination during pregnancy reduced the risk of getting the flu by about 70% compared to the control group. Vaccination during pregnancy also appeared to reduce the risk of fetal death slightly, but the reduction was not statistically significant.

Pregnant women tend to suffer more complications of the flu than non-pregnant women, in part because their immune systems are partially suppressed during pregnancy. So it’s important that they understand that they can get a flu shot without harming their babies. In fact, the flu vaccine may be good for the fetus/newborn as well as good for the mother; antibodies produced by the mother can cross the placenta (protecting the fetus) and are found in the mother’s milk (protecting the newborn for up to six months).

Wind Turbine Tax Credit is Renewed

Until the very end of 2012, industry experts were predicting that the construction of new wind turbines for generating electricity would decline by as much as 90 percent in 2013. That was because a tax credit amounting to about $1 million dollars per windmill was set to expire on Dec. 31, 2012. Wind turbine developers rushed a lot of new wind turbines into production in 2012 in order to take advantage of the credit, but had essentially no plans for new construction in 2013. Had the tax credit actually expired, more than 30,000 jobs might have been lost in the industry.

But the industry got a last-minute reprieve as part of the fiscal cliff negotiations in the final days of 2012. Part of the tax package included in the final fiscal cliff deal was an extension of the tax credit for wind turbine construction that begins in 2013, provided that construction is completed by 2014. That gives the industry some breathing room, at least for now.

Federal tax credits are sometimes used to encourage the development of new industries that may not yet be cost-effective. The wind turbine industry has been granted tax credits three times since 1990. This time around, concerns over the national debt mean that there is likely to be very little enthusiasm in Congress for extending the subsidy (amounting to over a billion dollars a year) yet again after this one expires.

Currently, wind energy accounts for 23 percent of all electricity generated from renewable resources, according to government statistics. The other renewable energy sources are hydropower (63%), wood and biomass waste (11%), geothermal (3%), and solar.

The Human Hand Makes a Good Fist

One of the defining features of humans is that the shape of our hands and fingers allows us to touch the tips of our fingers with our thumbs. As a result, we are able to pick up and manipulate very small objects – something other primates can’t do. Textbooks describe this human anatomical feature as having “opposable thumbs”. Allegedly it is a feature that has given us an evolutionary advantage.

Now researchers report that there’s another unique feature of the human hand that also confers an evolutionary advantage. According to a recent paper published in the Journal of Experimental Biology, the structural arrangement of the bones in the hand and the wrist allow us to make a very effective fist, for use as a weapon. The report demonstrates rather convincingly that when we curl the four fingers into the palm and then position the thumb over the index and second finger, the unique shape of the human fist allows the palm to buttress and support the fingers when we strike a blow. As a result, more force is transmitted by the knuckles than would be possible with the hand anatomy of other primates.

The authors of the study suggest that being able to use the fist as a weapon confers an evolutionary advantage. In other words, our hand evolved not only to be able to manipulate small objects easily, but also to fight effectively.

Being Overweight Is Not a Mortality Risk

In 2009 a study from Canada reported that slightly overweight people actually were at less risk of dying than people of normal weight (see this blog, July 9, 2009). That study generated a lot of controversy, understandably. One criticism was that the study included “only” 11,000 people, all of whom were Canadians; perhaps the results would not be not be generalizable to other populations.

Now a subsequent much larger study proves the Canadian study right. The most recent study is a meta-analysis of 97 separate studies of weight versus mortality that includes over 2.9 million people. The results show quite convincingly that people who were “overweight” by current government definitions (a Body Mass Index of 25-29.9) were 6 percent less likely to die over a given time period than persons of “normal” weight (BMI 18.5-24.9).

No one is suggesting that people should gain weight just to live longer. For one thing, mortality risk goes up dramatically for persons who are severely or morbidly obese. But the data do call into question the proper definition of “normal” or ideal weight. Perhaps the definitions of normal weight, overweight, and obesity need to be shifted ever-so-slightly to the right, towards slightly higher BMIs.

We may never have a true definition of “ideal” weight, because any such definition would probably have to take into account a whole host of other factors such as physical health and even happiness. But the current data does give one food for thought when it comes to understanding the meaning and value of government definitions of ideal weights.

Bone Deposition in Adolescent Women Who Smoke

A recent study published in the Journal of Adolescent Health shows that the rate of bone formation in adolescent women is negatively impacted by smoking (men were not studied.) According to the study, young women aged 13-19 who smoked at least one cigarette a day had lower rates of hip and lumbar spine bone mineral density (BMD) accrual than young women who did not smoke. (The lumbar spine and hip are common areas of osteoporosis later in life.) The effect was large enough to put the smokers’ rates of bone formation about a year behind by age 19. 

Osteoporosis in older women has been linked to lower rates of bone formation during adolescence, when most bone is formed.  So it is possible that the lower rates of of bone formation seen in young women who smoke could lead to an increased risk of osteoporosis later in life.  

It is not known whether young women who smoke would “catch up” in terms of bone formation if they were to quit smoking as young adults.  Further studies would be needed to test this hypothesis.