Chemicals found in perfumes and cleaning products can cross the placenta and reach the baby in the womb, research shows.
Some of the chemicals are found in cleaning products
Tests of umbilical cord blood shows many chemicals, ranging from those used to make plastics and artificial musks, are present.
WWF-UK and Greenpeace who produced the report want to see regulations to ban such substances in every day products.
But health experts said pregnant women should not be alarmed by the findings.
Crossing the placenta
They said there was no clear evidence that the chemicals were causing damage to unborn children.
For the report, tests were carried out on blood samples from the umbilical cords of 27 newborn babies and 42 new mothers.
The samples were tested for eight groups of chemicals, including those found in cleaning products and non-stick and waterproof coatings.
All of the samples tested positive for at least some of the 35 chemicals tested.
Some of the umbilical cord blood samples contained as many as 14, and two of the mothers tested positive for 17 of the chemicals.
The researchers said they were concerned by their findings.
Helen Perivier, Toxics Campaigner for Greenpeace International said: "It is shocking that such chemicals are in the human body at any stage of our life, let alone at the very start, when the child is most vulnerable."
Andrew Lee of WWF-UK said: "These chemicals should not be in products, let alone in developing babies."
THE 8 TYPES OF CHEMICALS
Alkylpheonols - found in detergents and pesticides; possible link with sperm defects
Artificial musks - found in perfumes; possible cancer link
Bisphenol A - found in tin cans and baby bottles; possibly effect on reproductive organs
Brominated flame retardants - found in textiles and electrical appliances; possible link with learning disorders
Organochlorine pesticides - present in some foods such as fish; possible cancer link
Perfluorinated compounds - found in non-stick pans; possible cancer link
Phthalates - found in PVC products like Clingfilm; possible birth defects and asthma link
Triclosan - found in toothpaste and deodorant; possible link with liver damage
The European Union is currently revising its chemicals policy.
Mr Lee said it was vital for the health of future generations that this legislation was effective and called for a wider ban on potentially toxic chemicals.
WWF said "safer alternatives" existed and should be substituted.
Professor Andrew Shennan, consultant obstetrician and a spokesman for Tommy's - the baby charity - said: "It's not that surprising that we find in the blood things that are in the environment.
"Mother and baby communicate directly, although the placenta does filter out some toxic substances.
"Without knowing that the substances are in some way harmful, it is difficult to gauge the potential seriousness of this finding."
He said the baby was able to deal with toxic substances in a similar way to adults.
However if they were exposed to something very harmful before birth and onwards, that might be damaging.
But he added: "It's not something to be alarmed about. These substances have probably been around for years and years.
"We are designed to live in hostile environments."