Pregnancy and Restrictive Diets: Why Consumer Tracking Is Not Enough

Start here

Pregnancy changes how the body handles food and glucose. Consumer apps and wearables are built for non-pregnant adults. This page is education only and not medical advice. If you are pregnant or planning to be and you are thinking about tracking, restricting food or using a glucose monitor, talk with your midwife or doctor first. For an urgent pregnancy concern, contact your maternity care provider or emergency services. Evidence labels: established, mixed, insufficient evidence.

What UK health service guidance says about dieting

This section draws on the NHS (UK). Advice in other countries may differ, so ask your own clinician.

• Pregnant women do not need a special diet, but it is important to eat a variety of foods every day. [1]
• There is no need to "eat for 2", even with twins or triplets. [1]
• Pregnancy is not the time to go on a diet, as it may harm the unborn child. [2]
• For women with obesity, the NHS says not to try to lose weight in pregnancy, as it will not reduce complications and may not be safe. [3]
• A folic acid supplement is recommended because it is hard to get enough from food alone. [4] For vegetarian, vegan and other special diets, the NHS points to specialist information. [4]

Strict rules from an app, such as fixed calorie, carbohydrate or "glucose score" targets, can run against this guidance. We found no research that supports consumer tracking as a way to guide dieting in pregnancy. Proper evidence not found.

Why adult glucose benchmarks do not apply

The best-known healthy-adult CGM benchmarks come from nonpregnant people with a nonobese BMI. [5] Pregnancy is different. In 32 healthy pregnant women monitored in a small German study, average glucose rose across pregnancy while fasting levels did not change. [6] A reading that looks "high" by adult wellness standards may be ordinary in pregnancy, and a reassuring reading may not exclude a problem. Do not compare a pregnancy to an app's adult target.

Gestational diabetes is checked clinically

Gestational diabetes is high blood sugar that develops in pregnancy and usually disappears after birth. [7] It does not usually cause symptoms, so it is often found through screening. [7] In the UK, women with risk factors are offered an oral glucose tolerance test, a blood test done in clinic. [7]

Clinicians are studying CGM in gestational diabetes. A 2025 review reported improved glucose control and high user acceptability, but mixed results for outcomes such as the baby's health, and said larger trials are needed. [8] That is clinical use under a care team, not an over-the-counter wellness sensor.

The FDA's March 2024 clearance of an over-the-counter CGM was for adults who do not use insulin. [9] We read the release and it did not discuss pregnancy, so whether such products suit pregnancy is not verified. The FDA also said users should not make medical decisions from the output without talking to a health care provider. [9]

Restrictive eating and eating disorders

Pregnancy can be a time of intense focus on food and weight. If restricting, purging or fear of eating is part of your life, or you track food compulsively, tell your maternity care team. See eating disorders and obsessive tracking for urgent resources.

Related guides

• Pregnancy and breastfeeding safety
• Preconception, pregnancy, postpartum and breastfeeding
• Misinterpreting normal variation in nutrition data