Why are my Mood Swings Back in the Third Trimester?

## Progesterone and Oestrogen

As usual, the two hormones responsible for mood swings, progesterone and oestrogen, are rearing their heads again. Progesterone actually reaches its highest concentration between weeks 28-40 [1]. Estriol, a type of oestrogen, also peaks towards the end of the pregnancy to get your body ready for childbirth and breastfeeding [2].

Progesterone is known to affect mood in many ways, these include its appearance within the brain and its conversion into cortisol [3]. Progesterone can pass through the blood-brain barrier easily meaning its concentration within some areas of the brain may be higher than within the bloodstream itself. These areas of the brain, notably the amygdala and hypothalamus, are associated with emotional regulation. Secondly, progesterone can be converted into cortisol leading to heightened levels of stress. Oestrogen also plays a crucial role in mood regulation, as it helps regulate progesterone [4].

## Fatigue and Tiredness

Pregnancy can be a physically and mentally draining time, where it is natural to feel lethargic and tired. In one study, 94% of pregnant women stated they had suffered from fatigue, the majority of which in the third trimester [5]. Emotional regulation can take a great deal of effortful cognitive control, which therefore means that fatigue could reduce this quality [6]. If you are feeling particularly tired and fatigued, it may be worth speaking with your doctor, and trying to prioritise your sleep. [The NHS](https://www.nhs.uk/pregnancy/related-conditions/common-symptoms/tiredness/ ) offers advice and guidance on ‘bump friendly’ sleeping positions and relaxation techniques that may help sooth the body and brain to allow for easier rest.

## Anxiety

Anxiety is felt by more than half of pregnant individuals (62.7%) [7]. Some anxiety can be completely normal, as you start to look forward to the delivery of your baby. However, anxiety can make it much harder and require more effort to regulate our emotions [8]. If you feel your anxiety is particularly troubling, you should speak with your doctor. You can also try mindfulness activities such as those listed in the Using mindfulness to help with mood swings: Harmonising emotions. (link article).