Hypertension in US pregnancies: 3% in 1989, 10% in 2024 — why?

Details in Claude AI

Hypertension pregnancy Claude.pdf

and

timeline, etc.

Ruled out:

More mothers with darker skin: the change in racial mix explains none of the rise.
Falling vitamin D: measured 25(OH)D within each group was flat or rising while hypertension surged.

Partly explains it:

Better recording on birth certificates. ( Broader diagnostic criteria (2013).
Older mothers.
Obesity contributes, but rates rose just as fast in normal-weight mothers (+79%) as in all mothers (+73%) from 2016 to 2024.
birth certificates didn’t record BMI until 2016

Open questions:

The strong birth-cohort effect: women born in 1996–2004 have 2.6 times the risk of those born in 1951–1959.
Why the US and Canada are rising while Norway and Australia are falling.
Candidate exposures such as ultra-processed food that haven’t been tested against the trend.

Health consequences of Hypertension while pregant

Hypertension in pregnancy harms the mother and the baby, both around the birth and for decades afterward. Preeclampsia and chronic hypertension carry most of the risk; mild gestational hypertension carries the least.

Mother: during pregnancy and just after birth

Death: hypertensive disorders are a leading cause of pregnancy-related death in the US. They account for about 7.4% of pregnancy-related deaths, and nearly a third of women who died during their delivery hospitalization had one documented. [[MMWR 2022](https://www.cdc.gov/mmwr/volumes/71/wr/mm7117a1.htm)] [Bruno 2022]
Heart attack and stroke: these are the severe complications most strongly tied to hypertension in pregnancy. [MMWR 2022]
Other complications, mainly with preeclampsia: stroke, retinal detachment, organ damage or failure, and eclamptic seizures. [PhillyVoice / USPSTF]
Placental abruption and organ failure are also on the NCHS list of maternal harms. [NCHS]
Eclampsia: the rate nearly halved in the US from 1989 to 2020. [Bruno 2022]
After delivery: blood pressure problems can persist or get worse in the weeks after childbirth, so postpartum monitoring matters. [NBC Palm Springs]

Baby

The fetal and newborn harms on the NCHS list are stillbirth, neonatal death, fetal growth restriction, preterm birth and low birth weight. [NCHS] Hypertension in pregnancy is the leading reason doctors deliver babies early. [Victoria 2025]

Risk depends heavily on the type of hypertension. In one hospital cohort (Karachi, 2019–2021), compared with mothers with normal blood pressure: [Pakistan cohort 2022]

Subtype	Stillbirth aOR	Preterm birth aOR	Low birth weight aOR
Gestational hypertension	1.39 (not significant)	1.54 (not significant)	0.98 (not significant)
Preeclampsia	2.66	5.71	5.45
Chronic hypertension	3.03	6.25	6.19

Absolute risks in US hospitals are likely lower, but the ranking by subtype is typical.

Longer term for the child: a meta-analysis of 61 articles found that children exposed to these disorders before birth had higher odds of autism (aOR 1.35) and ADHD (aOR 1.29). Findings for other neurodevelopmental outcomes were inconsistent. [Maher 2018, JAMA Psychiatry]

Mother: decades later

Outcome after preeclampsia	Relative risk	Source
Chronic hypertension	3.70 (mean 14 years later)	Bellamy 2007
Heart failure	4.19	Wu 2017
Coronary/ischaemic heart disease	2.16–2.50	Bellamy 2007 Wu 2017
Cardiovascular death	2.21	Wu 2017
Stroke	1.81	Bellamy 2007 Wu 2017
Venous thromboembolism	1.79	Bellamy 2007
All-cause death	1.49	Bellamy 2007
Cancer	0.96 (no increase)	Bellamy 2007

Hypertensive disorders of pregnancy are also linked to end-stage kidney disease later in life. [Swedish registry] The American Heart Association now treats a history of these disorders as a "risk-enhancing factor" for lifetime cardiovascular disease, with a 2- to 4-fold higher risk of heart failure. [Cameron 2022]

Why this matters for the trend

With about 1 in 10 US mothers now affected, this rise will feed into more maternal heart failure, chronic hypertension and kidney disease over the next 10–30 years. It will also add to early deliveries now.

Sources: