An alien in the belly – how the immune system adopts during pregnancy

Our immune system normally attacks and kills foreign organisms, tissues and germs in order to protect us. That is why those who have had an organ transplant have to take immunosuppressive drugs for the rest of their lives. So, how can a baby with 50% foreign DNA grow inside its mother’s belly without being rejected?   

The immune system is one of our most complex physiological systems. It protects us from foreign and potentially harmful invaders through a series of intricate processes involving many different types of immune cells. Normally, a fierce immune response is triggered if foreign tissue enters our body, aiming to kill and get rid of the invader.¹ The immune system hence has to be “reprogrammed” to allow the growth of the fetus – while simultaneously upholding an immune defense against true invaders such as virus and bacteria.^2,3  

To provide a safe pregnancy without complications, not only the mother’s cells need to tolerate the baby, but also the other way around.³ Despite being immature, the baby’s immune response is detecting and tolerating maternal cells.³ The placenta – an amazing organ that only exists during pregnancy – plays an essential role in facilitating the important cooperation between the two immune systems.¹ For example, if the placenta doesn’t attach properly into the uterine wall and molecules from the fetus leaks into the mother’s bloodstream, a condition called preeclampsia can develop.

Despite long believed to be otherwise, pregnancy does not suppress the mother’s immune system, the immune system is rather fine tuned in such a way that the baby can be tolerated.^2,3 The intricate way that the immune response is altered to selectively accept the growth of an “alien in the belly” is still not fully understood and awe inspiring for researchers who want to find ways to handle graft rejection after transplantations! 

What is a healthy weight gain during pregnancy?

It makes sense that someone who has a growing baby in the belly gains weight. However, many pregnant women are unhappy about their extra kilos and worried about putting on too much weight.¹ Learn about the factors that contribute to a healthy pregnancy weight gain!

Soon after fertilization the growing fetus is supported by a totally new – and fascinating – organ: the placenta. This organ weighs approximately 700 g at the end of the pregnancy.² The muscular wall of the uterus also grows, and together with the shock absorbing amniotic fluid, it creates a protective environment for the growing fetus. The baby, the reproductive organs (the uterus and the placenta) and the breast tissue represent close to half of the recommended added body weight (see table below).³ 

The mother’s blood volume also increases during pregnancy due to a higher demand for blood in her organs, but also as nature’s preparation for possible blood loss during delivery.³ Edema, i.e excessive absorption of water by the body’s cells, is also a common phenomenon towards the end of pregnancy.⁴ Overall, the increase in fluids accounts for nearly a quarter of the weight gain.³

Finally, almost a third of the increase in body weight is fat tissue. During pregnancy, energy is retained more efficiently than usual to ensure proper growth of the baby and as a preparation for breastfeeding.⁵ This is an advantage when nutrition is scarce, but in societies where energy rich food is available in excess, it can become a challenge. 

The mother’s BMI before the pregnancy indicates the recommended weight gain during pregnancy.³ See the table for guidance. There are several health problems associated with excessive weight gain, e.g. gestational diabetes, pregnancy related hypertension and retention of a higher weight after pregnancy.⁶

It is logic to think that a much higher energy intake is needed during pregnancy since the body is going through such an endeavor. However, that is not the case. In the first trimester only a little extra energy is needed: an additional egg or a slice of whole grain bread daily is enough. In the second trimester somewhat more extra energy is needed, but not more than a banana smoothie or similar. In the last trimester an extra bowl of chili con carne or baked salmon with potatoes daily gives enough extra energy.⁷

In summary, for you and your baby’s health you should continue with regular physical exercise and healthy food, just a little more than usual.

Food recommendations look different worldwide

Are you worried about the risk of eating certain foods during pregnancy? Relax! Food recommendations for pregnant women look different around the globe.¹

In India, pregnancy food charts state exactly what should be eaten at what time of the day, including a handful of nuts at 4 pm.² The charts are modified to suit women’s BMI, reflecting the vast differences in nutrition status of the Indian population.² Japanese guidelines for pregnant women similarly offer a pregnancy food plan, but for each day of the week. In addition to recommending vegetables, the Japanese food plan has a rather strong focus on seafood.³

In the Netherlands, precise amounts for each food product are stated, but there is no schedule.⁴ Sweden and Finland have even less detailed  pregnancy recommendations with pregnancy food charts focusing on the benefits of a diverse diet.^5,6

On the other hand, in the United States, expecting mothers are informed about food safety and how to avoid foodborne illnesses and harmful microorganisms. The focus is hence less on particular foods, but rather on hygiene practices when cooking.⁷ Pregnant women are for example given precise information on how to wash fruit and vegetables and instructions about how to heat certain foods.⁷ 

Despite local differences, there are globally well established recommendations to keep a good health during pregnancy, such as the intake of folic acid supplements, the avoidance of alcohol and the importance of a versatile diet combined with exercise.⁸

If you feel stressed about what you can or cannot eat, take a deep breath and remember that mothers around the world eat very different diets and that healthy babies are born everywhere.⁹ With that in mind,  check your country’s pregnancy diet recommendations and enjoy your meals!

Examples of daily food plans (India and Japan) and food recommendations (The Netherlands) for pregnant women. Amounts per day. 

Are you suffering from fear of delivery?

Up to 20% of pregnant women suffer from fear of childbirth, but this type of severe anxiety can also affect co-parents.

The upcoming delivery will inevitably be a big event in your life. Nervousness or unrest are normal feelings, but some pregnant women experience high levels of anxiety and can develop a more serious condition called fear of childbirth (FOC). This can range from mild to severe anxiety, the latter sometimes being referred to as tokophobia.¹ 

FOC and tokophobia has been shown to affect about 5-20% of all pregnant women, depending on how it is measured.² However, it is important to know that neither FOC nor tokophobia are feelings limited to those giving birth. Also, co-parents can suffer from anxiety and fear related to childbirth. Research in this area is still limited, but estimations say that as many as 1 out of 10 partners may suffer from FOC.³

Traumatic events in the past, fear of not being in control and fear of pain have been shown to be associated with FOC.² Some women are also afraid that their body might not be strong enough to give birth.⁴

What can you do if you are pregnant and feel anxiety or fear when thinking of the delivery? Research suggests several ways in which anxiety can be relieved: the first and most important step is to talk to your midwife to get accurate information about the delivery process.¹ Sharing your fears with a knowledgeable professional might also be helpful, as well as cognitive behavioral therapy. At many hospitals there are specialized centers for those who suffer from FOC.¹ 

Next time you meet your midwife, share your feelings and thoughts. You are far from alone, and there is help available!

Aspirin reduces the risk of preeclampsia

Preeclampsia affects 5-8% of all pregnant women annually and is a hypertensive condition that globally is one of the main causes of maternal mortality and morbidity in mothers and fetuses.¹

A large number of research studies have shown that one 75 mg tablet of aspirin per day significantly reduces the risk of preeclampsia.² In some countries, among them Sweden, healthcare authorities therefore have introduced routines for preventive treatment with aspirin. Women belonging to the risk group are recommended to prophylactically take 75 mg of acetylsalicylic acid from week 10-12, until week 36.³

Preeclampsia is a complex condition and researchers have not yet fully understood its underlying causes.¹ The disease is characterized by the placenta not properly attaching to the uterine wall, causing substances that normally only are present in the fetus to enter the mother’s blood stream. The nutrient supply to the fetus also deteriorates.¹ The mother’s immune system gets triggered by the unknown substances, giving an inflammatory response that damages the blood vessels and causes them to contract.^4,5 This in turn causes proteins to leak into the urine and the blood pressure to rise.⁴

Preeclampsia can appear from pregnancy week 20, but usually shows as late as after week 34. The symptoms vary greatly, which makes the condition difficult to diagnose, but typical symptoms are headache, visual problems, swelling or acute pain in the upper abdomen, especially under the ribs on the right hand side.⁶ Anyone who experiences symptoms such as these during the latter part of pregnancy should contact healthcare.

At present, there is no other available treatment than to deliver the child prematurely.³ However, blood pressure-lowering medication, reduced stress and monitoring in hospital are measures that can be put in place to postpone a possible premature birth.⁴ Normally, the symptoms disappear shortly after the baby is born.

Pregnant women with one high risk factor or three or more medium risk factors are considered to belong to the risk group that can benefit from taking Aspirin. Important! Never start any medication on your own, please consult your doctor before starting any medication.

Interview with Pregspect’s researchers at Uppsala University

Read the article  “New model forecasts birth dates” from Uppsala University, Sweden 2022 , where researchers and  Pregspect founders Dr. Mikael Elinder and Dr. Oscar Erixson are interviewed about the background to Pregspect and the work involved in developing the birth forecast models.

Link

Do you know why to eat folic acid?

Everyone needs folate (vitamin B9, or folic acid), but it is especially important when you are pregnant or planning to get pregnant.¹

Folate is used by the body for DNA replication (cell division) and in the production of amino acids and vitamins.¹ Since it is necessary for the formation of red blood cells, folate deficiency leads to anemia. During pregnancy the need for folate is higher than normal since it is also required for growth and proper development of the fetus.¹

Several studies have shown that a daily intake of folic acid before and during pregnancy can reduce the risk of neural tube defects (NTDs) by up to 72%.² NTDs are among the most common birth defects, contributing to miscarriage, infant mortality and severe congenital abnormalities.¹ Since folate supplement was introduced as a recommendation to women worldwide, the number of children born with NTDs has dropped significantly.¹ The finding that folate can reduce NTDs is one of the rare instances in which science has been able to identify preventable causes of birth defects.³

Folate is a vitamin B found naturally in food, while folic acid is an artificially produced folate that is used as food fortifier and in dietary supplements. Folic acid is more easily absorbed by the body than the folate form.³

Egg yolk, dark green leafy vegetables (e.g. asparagus, broccoli, spinach and avocado) and various kinds of cabbage, beans, chickpeas, lentils, sunflower seeds, fruits and berries are examples of foods high in folate. The vitamin is heat sensitive and can be easily destroyed by prolonged heating, so fresh vegetables are preferred.⁴ However, to get enough folic acid during pregnancy, supplements are usually recommended.