The First Trimester: What to Expect

The first trimester runs from conception to the end of week 12. It's the period when the most dramatic developmental changes take place, when the embryo forms its major organs and structures, and when many people experience the most significant physical symptoms of pregnancy. It's also, for most people, the period before the pregnancy is widely known, which means navigating a significant physical and emotional experience largely in private.

The gap between what pregnancy is supposed to feel like (glowing, joyful, obvious) and what it can actually feel like (exhausted, nauseous, anxious, and uncertain) catches a lot of people off guard. Understanding what to expect, and what's within the normal range, is reassuring in a way that the more curated portrayals of early pregnancy simply aren't.

Nausea and sickness

Around 80% of pregnant people experience nausea in the first trimester, and for roughly a third of those, it involves actual vomiting. Despite being called morning sickness, it can occur at any time of day and for some people is essentially constant. It typically peaks around weeks 8 to 10 and for most people resolves by the end of the first trimester, though some experience it throughout.

The cause isn't entirely understood, but is likely related to rising levels of hCG and oestrogen. Eating small amounts frequently, keeping something in the stomach at all times, and avoiding strong smells or foods that trigger symptoms are the practical measures most people find helpful. Cold foods and plain carbohydrates, crackers, plain toast, rice, tend to be better tolerated than rich or strongly flavoured foods for many people.

Hyperemesis gravidarum is a severe form of pregnancy sickness that involves persistent vomiting and can lead to dehydration and significant weight loss. It affects a smaller proportion of pregnant people but requires medical support. If sickness is severe, persistent, or preventing you from keeping any food or fluids down, it's important to speak with your midwife or GP promptly.

"The first trimester is one of the most physically demanding parts of pregnancy, and the least acknowledged. Being kind to yourself during it isn't optional."

Fatigue

First-trimester fatigue is often described as unlike any tiredness experienced before. It tends to be deep, pervasive, and unresponsive to rest, driven by the significant increase in metabolic activity and progesterone that early pregnancy involves. Many people find it affects concentration, mood, and the ability to function normally. This is entirely normal and almost universally temporary: energy usually returns in the second trimester.

Rest as much as is possible and practical, without guilt. The body is doing something demanding, and the fatigue is a reflection of that.

The emotional reality

Pregnancy involves a rapid and significant hormone shift that affects mood alongside everything else. Many people feel a mixture of excitement, anxiety, and uncertainty in the first trimester that is quite normal and doesn't need to be suppressed. Some people feel a persistent low-level anxiety about the pregnancy continuing safely, particularly after a previous loss or following fertility treatment. This is understandable and worth talking about, either with a partner, a midwife, or a counsellor.

Not everyone feels immediately bonded to or joyful about a pregnancy in the first trimester. This is more common than it tends to be acknowledged, and it doesn't predict how you'll feel later.

Practical things in the first trimester

Register with a midwife as soon as you have a positive pregnancy test; the booking appointment is usually around weeks 8 to 10 and involves an initial assessment and information about your care pathway. Folic acid should be taken from as early as possible and continued to at least week 12. The 12-week scan, usually offered between weeks 10 and 14, is the first opportunity to see the pregnancy on screen and includes a screening test for chromosomal conditions if you choose to have it.

The first trimester is one of the hardest parts of pregnancy to get through, and also one of the least acknowledged. Knowing that is, at least, something.