Posts Tagged ‘low blood pressure’

Heart and circulation

  • When you are pregnant sudden demands are placed on your body’s heart and circulatory system – a growing baby and your increased body weight, and now you are exercising – that’s another demand.
  • Slowly the volume of blood circulating in your body increases, so much so that by the end of your pregnancy you may have 40 % more circulating blood.
  • Although there is an increase in red blood cells to carry more oxygen round the body, hormones from the heart and adrenal glad cause the body to hold onto more salt and water.
  • This leads to an increase blood volume (but from blood plasma rather than red blood cell mass).  At times this can increase feelings of fatigue during the day, and play a part in pregnancy anaemia, known as physiological anaemia.

Heart Rate

  • To accommodate the extra demands your overall blood volume will increase.  Your heart chambers expand, the amount of blood your heart pumps during each beat increases (by up to 15 bpm).  This means that your resting heart rate will be increased and exercise will elevate your heart rate quicker (even if you were pretty fit before pregnancy).
  • Because of this duration and intensity of any exercise class needs to be modified, so to the warm up and cooldown.


  • We cannot live without breathing (in fact Pilates said “Above all, learn how to breathe correctly”).
  • The air we breathe ultimately makes its way to baby, via the placenta  and umbilical cord.
  • Carbon dioxide sensitivity is increase by the hormone progesterone (see here for more details) which makes simple tasks like walking up and down stairs more breathless.
  • It means you are working harder and responding to changes in your respiratory system – not that your are not fit.
  • During the end of your pregnancy there is a demand for up to 20% more oxygen than pre-pregnancy; combine this with the increased carbon dioxide sensitivity your breathing will become faster and you are more likely to become breathless as the body tries to expel the increased levels of carbon dioxide.
  • As baby grows the diaphragmatic movement becomes restricted, which means the diaphragm cannot move as freely as it once did, and reduces your ability to inhale a full breath.  This too can make you feel breathless.
  • Hormones accommodate this by allowing the ribcage to flair outward, thereby allowing the same volume of air into the lungs, but by another mechanism.
  • This flaring can cause some pain or discomfort around the ribs or mid back.  However, once baby’s head is ‘engaged’ this usually goes and your might feel a huge release – allowing you to breathe better!
  • Breathe at your own rate and tempo – don’t work too hard – make sure you can hold a conversation whilst exercising.
  • Don’t breathe too deeply or rapidly as this may cause you to hyperventilate – you will know as you will feel very dizzy , clammy and look pale.  If this happens, cup your hands over your mouth and nose and breathe normally until you recover.

Initial vascular under-fill

  • In the very early stages of pregnancy hormones initiate reduced response and relaxation in blood vessels and muscle cells.
  • This means that the heart, arteries and veins increase their elasticity and volume almost immediately.
  • The effect of these changes means that for a short rime there is not enough blood to circulate; blood pressure will fall – (called vascular under under-fill).
  • You may feel light-headed if you stand still for a long while or on standing if you have been seated for a while.
  • It would be sensible to avoid either of these positions, and also consideration needs to be given when getting up/down from the floor.
  • Seated or all-four positions may be more comfortable and reduce the effects of low blood pressure.
  • If you feel unwell you must consult your health care professionals.
  • Symptoms often disappear by week 20, but some may persist during the pregnancy.

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Whilst not wanting to delve into the human physiology at full speed, there are a few considerations with regard to exercise and pregnancy.  When you are pregnant there is a huge amount of change – some might be unrecognisable at times!


  • During the early stages they can be tender and sore, which might mean you are not comfortable when lying prone (on your tummy)
  • You might need better support bras when taking part in any activity.  Make sure you have a fitted bra (by a bra-fitting expert if you can), and make sure your regular, everyday bra’s remain comfortable.
  • During the duration of your pregnancy the size and shape of your breasts will alter a lot.  Fatty tissue is laid down, milk-producing tissue is formed – these are all normal changes.


  • The hormones again play a part in the condition of your skin; some may have quite a change, whilst others notice hardly anything.
  • You may find you get a dark line down the front of your tummy – known as ‘linea negra’.
  • These skin changes revert back after baby is born.
  • Often the facial skin pigmentation changes, known as ‘the mask of pregnancy’.
  • Stretch marks may also appear, usually on the breasts and abdomen, but can also appear on the thighs and hips.  Trying not to gain too much excess weight might help, but genetics and a bit of luck might also help!
  • One change that is important that your skin makes is that you will sweat more easily – the body is able to deal more quickly and efficiently with an increase in body temperature.  You sweat, so you dissipate unwanted heat.

Bladder and kidney changes

  • The combination of the pregnancy hormones and the growing uterus affects the latter – you might feel you need to go to the loo more often.  This is normal and you shouldn’t cut down on your fluid intake.
  • When the weather is warmer, make sure you drink enough water to keep hydrated, and only exercise at moderate levels.
  • At the later stages of your pregnancy you might notices that you naturally retain more water – your feet, ankles and legs may swell.
  • Exercise can help reduce this fluid retention (oedema) by boosting circulation.
  • If possible elevate you legs and avoid standing for long periods.  If you do stand for long periods of time you might find support stockings useful, but don’t expect to be asked out on any dates when wearing them!!!!
  • After the birth some women find that they have stress incontinence (small leaks of urine when they cough, sneeze or laugh.  The inclusion of pelvic floor exercises throughout your pregnancy can help with that.


  • Insulin levels also increase during pregnancy and a small number of women develop gestational diabetes (see here).
  • Symptoms include constant thirst and excessive urination.
  • If you have been diagnosed with gestational diabetes then you will require medical supervision and it being controlled before you are able to resume/start exercising.
  • The condition normally disappears after pregnancy.

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As you (and others around you) may notice, there are a number of natural hormonal changes happening throughout your pregnancy.  Your moods may swing from one end of the spectrum to the other, and then you might be like nothing has happened!    Understanding why these hormones play havoc with us will help you cope with the emotional and physical changes that are happening.

Though each person will have a different story, the effects of the hormones are the same:

  • Missed periods
  • Nausea, possible vomiting
  • Breast tenderness
  • Tiredness
  • Moods swings
  • Urge to go to the loo more

The main three hormones which affect our bodies during pregnancy are:


  • Uterine growth during pregnancy – up to 1000 times in volume – 5 litres.
  • Weight increases from approx 45 grams to 480 grams.
  • Normal weight gain in pregnancy is influenced by Oestrogen, and also affects how the fat is distributed.
  • Possible pre-cursor for another hormones, Relaxin


  • Helps relax smooth muscle tissue, including the gastrointestinal tract (hence heart-burn)
  • Increases sensitivity to carbon dioxide causing you to feel out of breath more easily
  • Respiration increases as your body works harder to get rid of the carbon dioxide.


  • Produced very early on in pregnancy (within the first couple of weeks), until the five to six weeks post delivery (and possibly remain whilst you are breast feeding).
  • Its main role is in relaxing ligaments and fibrous tissue; preparing the body for the carrying and delivery of the baby.
  • Relaxes ligaments around the pelvis, (allowing the joints to move to aid with childbirth).
  • It also relaxes other ligaments in the body, again making joints more elastic.
  • Relaxin works by increasing the amount of water in the collagen which makes up ligaments and tendons, allowing them to become more elastic.

It is mainly due to the presence of relaxin that exercises need modifying to meet the needs of the pregnant exerciser.  Relaxin makes joints less stable and as such stretches and some exercises need to be modified, and also means that mums-to-be are more prone to injury during activity and are less stable generally.

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