Blood Pressure in Pregnancy

I was recently asked some questions regarding blood pressure during pregnancy by my colleagues at Physiquality. In preparing material, I wrote this blog, which includes very basic clinical information and explanations about this topic.

What is the normal range for blood pressure for pregnant women? What readings would fall under high blood pressure?

Blood Pressure (BP) in pregnancy is a complex topic.

First, we need to know: What are the classifications of BP?

The chart below is from the evidence-based 2014 Guidelines of the American Heart Association and the National Heart, Blood and Lung Institute of the NIH. The first number is Systolic BP or during the heart beat. The second number is Diastolic BP or between beats. These numbers are relevant for women of childbearing age.

  • Normal                        <120 mm Hg and <80 mm Hg
  • Pre-hypertensive          120-139 or 80-89
  • High BP Stage 1            140-159 or 90-95
  • High BP Stage 2            ≥ 160 or ≥ 10

Why does low BP (hypotension) occur in a healthy pregnancy?

A healthy pregnant woman with normal BP and no cardiovascular or immune system complications, will have pregnancy BP lower than her non-pregnant BP due to increased progesterone relaxing her vasculature. To create the placental and uterine blood flow, blood volume (V) expands rapidly increasing by around 40%, but stroke volume increases less, so beats per minute (pulse) may increase, systolic BP may drop 5 mm Hg and diastolic may drop 10-15 mm Hg. If V is not adequate with this relaxed vasculature, BP may drop even lower. To help maintain normal BP, women are encouraged to drink sufficient water (about 8 glasses/day) and eat enough protein (about 20-25% of daily intake) to produce a blood volume that will sustain an adequate BP. Other more severe conditions – often genetic – may also be relevant, such as postural orthostatic tachycardia syndrome.

Other causes of hypotension include lying still on the back with legs extended for long periods of time after the first trimester. The weight of the uterus impinges on the vena cava returning blood to the heart, thus reducing BP and blood flow to the uterus and placenta. Also, standing for long periods of time with a minimum of motion, as happens with teachers, cashiers, line workers and nurses in the second half of pregnancy when increasing relaxin and elastin cause further softening of vasculature. This results in difficulty returning blood from the lower limbs and reducing blood flow to the uterus and placenta.

What are hypertensive disorders of pregnancy?

According to the National High Blood Pressure Education Working Group on High Blood Pressure in Pregnancy, hypertensive disorders of pregnancy are presently classified into four categories:

  • Chronic hypertension (pre-existing)
  • Preeclampsia-eclampsia
  • Preeclampsia superimposed on chronic hypertension
  • Gestational hypertension

[The Society of Obstetricians and Gynecologists of Canada categorize these disorders as pre-existing or gestational, with the addition of preeclampsia to either category.]

Chronic hypertension is BP >140/90 prior to pregnancy or before 20 weeks. New onset of high BP after 20 weeks may indicate preeclampsia (PE), which requires further consideration. PE involves other symptoms and organs. It occurs in about 5% of all pregnancies, 10% of first pregnancies and 20-25% of women with a history of chronic hypertension. It is a serious disorder and major cause of adverse maternal and fetal outcomes, including strokes, seizures and restricted fetal growth and development.

The underlying pathogenesis of preeclampsia-ecclampsia is not yet fully understood, but is a fundamental dysfunction of the placenta leading to endothelial dysfunction and vasospasm. Possible causes include pre-existing endothelial dysfunction, metabolic dysfunction, auto-immune responses and infection. It is likely that the placenta is affected very early on, during implantation, trophoblast invasion of the uterus and opening of the spiral arteries to form the blood pool on the maternal side of the placental circulation.

Gestational hypertension is the onset of BP >140/90 after 20 weeks without other features of preeclampsia. About 1/3 of these women develop preeclampsia. Gestational hypertension is highly associated with hypertensive disorders later in life. Diabetes can also be a factor associated with hypertension.

Whenever a woman has elevated BP in pregnancy, she needs to be evaluated and have a follow up course of observation and treatment. At its most severe, a hypertensive disorder can affect all the body’s organs and systems, and can be fatal.

What can pregnant women do (diet, exercise, healthy habits) to keep their blood pressure within a normal range?

Some risk factors for hypotension or hypertensive disorders of pregnancy are inherited, others are a consequence of behavior, and many are a combination.

What can a woman do before pregnancy?

Because the events that pre-dispose a woman to hypertensive disorders may occur before she knows she is pregnant, some efforts at prevention may be helpful in the six months to a year prior to pregnancy. Preparing for the implantation period by maintaining optimal health and fitness is likely the most helpful behavior. Cardiovascular or aerobic fitness, which prevents or reduces the severity of endothelial dysfunction is highly valuable. An adequate daily nutrient intake along with sufficient water, and maintaining a BMI <25 are important factors. Women with elevated blood pressure should discuss with their care provider the balance of sodium and potassium intake, along with the total allowable amounts.

Avoiding infections or illness around the time of conception may be a factor. Hypertensive disorders are mediated by inflammation. Unfortunately, another factor may be the maternal immune response to the fetal DNA. This may also be dependent on combined maternal/paternal immune system responses.

What can a woman do once she is pregnant?

Once a woman is pregnant, maintaining optimal health and fitness continue to be important. Even if there are pre-disposing factors for disorders, she may be able to reduce the severity by staying fit, well nourished and well rested. A balanced and colorful diet, along with avoidance of alcohol, drugs and unsafe behaviors are critical.

The ability to achieve the Relaxation Response, meditation, deep breathing and hypnosis are valuable for acute BP reduction. Each of these skills is mediated by the parasympathetic nervous system response (or alpha brain rhythm) and mitigates the effects of stress on a temporary basis. Cardiovascular or aerobic fitness is effective for long-term BP reduction, as well as cardiovascular health.

Resting on the left side maximizes circulation and – if possible – finding 15 or 20 minutes to rest this way during the day is beneficial, especially if a woman’s work involves standing for long periods of time. Avoiding lying on the back or standing for long periods of time is advisable. Finding a community of support for having a healthy pregnancy can be a great asset, as well.

The 51% Factor: Pregnancy, Power & Health

Recently I came across this posting and thought it worth posting again. On one hand I see signs of continuing progress, and on another hand it seems to me there are fundamentalist influences popping up everywhere (including among U.S. evangelists) that threaten women’s right to reproductive freedom and health. There is no end to the need to be vigilant.

In the U.S. and most of the developed world, approximately 51% of the population is female. Most females give birth at some point in their lives, although, in any year, only about 2% of the population gives birth.

No one living on earth got here any other way than gestation, so there ought to be some power attached to being part of that 51%. Historically, it might be said that the power has been merely for survival…the good breeders survived long enough to produce heirs and those who lived on knew where the roots and fruit grew.

Only women can make more people with their bodies.

Here are some things to consider:

  • Women make people
  • Women’s health and fitness before pregnancy affects whether the pregnancy is healthy
  • Women’s health and fitness during pregnancy affects her lifetime health and that of her offspring
  • Maternal survival is important to offspring well-being
  • Maternal health and fitness affects maternal adaptation and thereby offspring well-being

Thus, is it not a sanguine notion that the health and survival of women is critical to the health of everyone? After all, the health of nations is associated with this slight majority of females, and the wealth of nations is associated with its health.

The good news is that people working from this understanding are making some headway around the globe. Recently, the World Health Organization noted that maternal death among pregnant and birthing women world-wide has been dramatically reduced from the 1980’s to recently. This is very good news!

Here is the interesting footnote:  Maternal death in the U.S. has risen 42% in the same period. While the absolute numbers remain small, this is a disturbing picture. What could be causing this?

Time will tell if we can figure it out and fix it. I venture to suggest some directions for consideration:

  • The elevated cesarean birth rate with its sequellae of cardiovascular and immune system disorders
  • Obesity
  • Metabolic syndromes
  • Diabetes
  • Heart disease

Why am I hopeful, then? I see among our current educated generation of new moms and moms-to-be a willingness to exert their influence – as breeders – over the health care scene. They want less technological birth. They want support. They want more information. They want to be healthy. These are wonderful things. I salute these young women…they also make my job easier in the process.

In addition, I see among young health care practitioners an understanding of the value of these things. Among practitioners working in public health clinics there is a sense of desperation on the one hand that the poor and indigent have no capacity or will to take care of themselves. On the other hand, the first step is always education and there are a lot of people working on this issue.

Which brings me to the closing point:  How do we bring more resources and intelligence to helping women be healthy, prepare for pregnancy, have healthy babies, reduce pregnancy complications, and improve infant and maternal death rates? I, for one, will keep blogging on this issue. You, I hope, will vote for people who understand this issue. The political power and will is in our hands.

51% of us are women…some day 51% of us can set priorities

Pregnancy Pathway, Outcome – Mom & Baby Health Status

This 2/1/2010 entry seems to draw attention consistently, so we decided it was worth re-posting it. The discussion concerns determinants of the health outcome for mom & baby in the Pregnancy Pathway. It reviews the pathway, and then continues to the last stage of the Pathway, the health outcome. Here’s the whole graphic:

So, the big question is: How can we predict the health outcome of mom and baby, given all the variables of preconception, conception, pregnancy, labor and birth?

Well, there are some things for which we can predict or estimate risk/benefit ratios, and there are some for which we cannot. Let’s start by going over the major things that are not very predictable. At the moment, genetics is pretty much unpredictable. Down the road…maybe…but for now, not so much. Some IVF labs claim they can slightly slightly increase the odds for one sex or the other.

Post-conception, chorionic villi sampling and amniocentesis are methods by which the genetic make-up of the fetus can be identified. These are done mainly to give parents a choice about continuing a pregnancy if there is a question about genetically transmitted disorders or conditions, such as Down Syndrome. But, for now, the best way to manipulate the genetic odds of health outcome for your offspring is to mate with someone who is healthy and has health-prone genes!

Once you are pregnant, it is clear that prenatal health care, exercise, healthy nutrition, stress management and adequate sleep play significant roles in increasing the potential for a healthy outcome for mother AND baby. In fact, not only short term, but also long term healthy outcomes are linked to these factors. These are factors within our control.

Risk factors – most of which are within in our control – that can adversely affect outcomes include environmental toxins, risky behaviors (unsafe sex, drinking, smoking or drugs), poor nutrition, sedentary behavior, stress and isolation (lack of social support). These risks, as well as the benefits, are all discussed in the previous posts.

At this point, it is important to note that there is a lot that goes into making a healthy pregnancy, birth and outcome that is within the control of the mother, providing she has family and/or social support to take good care of herself.

The labor process and birth mode can also affect health outcome, but in general the effect is short-lived. For moms who have received regular care and are in excellent health, the occurrence of a truly devastating birth outcome for mother and/or baby is extremely rare. The exception may be mental or emotional turmoil that can accompany a difficult, unexpected and uncomfortable situation, such as an unplanned cesarean birth.

 

Group exercise programs are a source of social support.

Three interesting research outcomes point to the importance of exercise groups. One is that exercise can help prevent some disorders of pregnancy, such as preeclampsia or gestational diabetes. Second is that the health benefits of exercising during pregnancy and the postpartum period are beneficial for both short and long term for mother and infant. Disorders of pregnancy are risk factors for future cardiovascular disease and metabolic disorders. Third is that exercise is most likely to occur when there is good social support.

Moving together is a “muscle bonding” experience that helps bind moms-to-be and new moms into a community of support. Within the group, moms can get help with tips for healthy eating and living, along with the support of others who know what she is experiencing. There are a lot of ways to get adequate exercise. When you are pregnant or a new mom, an exercise group can be one critical path to health and well-being.

Mother’s Day for the Compassionate

Mother’s Day is an important day!  It is set aside because – let’s face it – without our mothers, none of us would be here. Not only do moms carry us inside their own bodies for those critical nine months, but once we are here our mom, or someone who can sub for our mom, is essential to our early survival.

For moms, moms-to-be and those with moms, here is something else to consider: Many presents celebrate motherhood. We can also give gifts that save mother’s lives, help them nurture their children, and improve the lives of families in our own countries and the developing world.

Here are a few groups to which you might want to consider giving this year. By donating to these organizations you can help improve the lives of mothers and children. Most will send a card or email message to the mom in whose honor you give the gift.

UNICEF Inspired Gifts.  You can choose gifts that improve education, water, health, nutrition, emergency care and other factors that affect the well-being of women and children.

White Ribbon Alliance for Safe Motherhood. You can advocate for every mother and every child in 152 nations when you give to this organization.

International Confederation of Midwives. This group exists to raise awareness of the global role of midwives in reducing maternal and newborn child mortality.

The Fistula Foundation. This group exists to raise awareness of and funding for fistula treatment, prevention and educational programs worldwide. Fistula is the devastating injury cause by untreated obstructed labor.

The Preeclampsia Foundation. This organization supports research to prevent and treat one of the most dangerous disorders of pregnancy, one that accounts for a large percentage of premature births and low birth weight infants. Having preeclampsia is also a risk factor for later heart disease for the mother.

March of Dimes. The “mother” of all charities for helping prevent and treat disorders and diseases that affect children.

Happy Mother’s Day to you and – hopefully – to all mothers everywhere!

One World Birth, Video Trailer

This is a must see…

http://www.youtube.com/watch?v=sCPZrK8C2ZY&feature=player_embedded

Birth and Human Survival

Ever wonder if humanity will become extinct sooner rather than later?

Animal Planet program on sea turtles…hatchlings crawl across the sand to the ocean and the commentator remarks that only one in a hundred will survive to adulthood. Those who escape the pelican beaks or salt water crocodiles waiting for them on the sand may meet with sharks or other swimming predators. Not good odds. Conclusion:  No wonder they lay huge numbers of eggs in the sand.

But, what would the result be if the turtles figured out some way to destroy all these predators so that most of each hundred survived?

New Jersey has just completed a brief bear hunting season in which about 500 bears were killed by hunters because another species that competes with them for space and food has over-populated that space. The close interface of bears and humans resulted in a situation in which the natural predator (bear) was overcome by the competing creature (human) who figured out how to destroy the predator.

Human beings have been party to a number of species’ extinctions or near etinctions because of our capacity to use technology to overwhelm the natural process of competing for resources. Nature has a way of balancing out the advantages that one species gains over another, but the use of advanced technology – everything from guns to in vitro fertilization – oversets this natural order. Essentially, we are working on having more and more surviving members. Check it out:

What questions does this thinking raise for those of us concerned about the safety of birth?

How do we make birth safer throughout the world while at the same time address the issue of over-population? There was a time when the capacity to overset nature worked to human advantage. The notion of “go forth and multiply” worked for us much as it currently does for the sea turtles. But that balance has changed. Essentially, the difficulties of establishing family planning as accessible and acceptable behavior for women goes hand in hand with aiding women in having safe pregnancy and birth, as well as supporting infant survival. For directly working on this issue, a thank you    is due the Bill and Melinda Gates Foundation.

How do we balance women’s need to work, the trend in developed nations to delay childbearing, the dangers of childbearing too young, and the need to reduce population? A hard question we need to ask is whether it is a “good” thing to have a child at 55 or 60. We know it is not safe for 12 year olds bear children. Yet, we go to extreme, expensive lengths to permit older women to have this experience while we spend very little on projects to prevent the atrocity of coerced reproduction in young women and girls.

So, the turtles and bears got me thinking scary thoughts:

  • What are the odds that the human population is growing so fast we cannot sustain safe water and prevent or quarantine infection sufficiently to avoid major epidemics that kill most of us?
  • What if engineered food products turn out to be not so good for us?
  • What if we so disturb the food chain by causing extinctions that we upset our food supply and end in chaos?
  • And, how does climate change fit in to all this?

Why would we allow this? Oh, right, greed. Growth is how economies are sustained. Have to work on that, folks.

Okay. I’ll stick to writing about enabling healthy pregnancy for now. But, let’s all work on raising awareness of the need for family planning.

Active Pregnancy – the rationale

Moving into Motherhood

It’s time to hit the main theme again:  Aerobically fit women are at reduced risk for things that go wrong in pregnancy, improve their tolerance for labor and birth, and recover more rapidly in the postpartum period.

The arrival of the holidays provides a good reason to bring this up, yet again! Pregnancy is a gateway time in women’s lives…we become more aware of our bodies, our sensations, our feelings, our needs, and how versatile and amazing our bodies are. We can make people with our bodies! During pregnancy, we often take precautions…we eat more carefully, avoid toxins, try to avoid stress. When the holidays arrive, we see indulgent behavior in a different light.

Yet, even with all this focus on behavior, we sometimes miss the biggest aid to a healthy pregnancy:  physical fitness. Research clearly demonstrates that fit women do better, are healthier and happier. More and more in the U.S. we see disorders of normal organ function that accompany sedentary pregnancy.

Let’s look at this a little closer (yes, I am going to repeat myself some more, but it is an important concept to spread). We live in a body model that rewards an active lifestyle.

Being sedentary causes things to go wrong

Not moving creates biochemical imbalances because the cardiovascular system atrophies and molecules created in the brain or brought in through the digestion may not get where they need to go for a healthy metabolism.

Your cardiovasculature is the highway that brings usable substances to the place they are used. You have to help it grow and develop, use it to pump things around and give it a chance to be healthy. Aerobic fitness does all these things.

Advice for young women of childbearing age

If you are thinking of pregnancy, have recently become pregnant, or work with women of childbearing age, we encourage you to open avenues of activity for yourself or others in this population. You can learn more from our website dancingthrupregnancy.com. You can also read backwards in this blog to get specific ideas. Or, you can seek out local pre/postnatal fitness experts (you can also do this on our site). Yoga is nice…we use some of it in our work, along other specific exercises for which there is a direct health benefit. But, we also see yoga converts who come into our program in mid pregnancy unable to breathe after walking up a flight of stairs. How will they do in labor? Not as well as those who have been doing aerobic dance or an elliptical machine 2 or 3 times a week.

The AHA/ACSM guidelines for the amount of aerobic exercise needed to improve cardiovascular status hold true for pregnant women just as they do for the rest of the population – a minimum of 150 minutes of moderate, or 75 minutes of vigorous, or a combination of these levels of intensity, per week. If you are not getting this level of activity, you are putting your health – and that of your offspring – at risk.